I mean, can't Germany do this former nations that were formerly part of Russia?
Potentially, but I think unlikely. There are fundamentally different geopolitical and geo-economic realities at play here that make it unlikely for Germany to pursue a "liberal" hegemony, and instead a more traditionally militaristic, coercive one.
First, the United States is on another hemisphere from the nations it supported economically. Balance of threat means that due to geographic proximity, there's no real question about building up a friendly nation on the other side of the hemisphere; direct (or indirect) control is costly, and moreover even if they build up their offensive military capabilities (instead of strictly defensive ones), it is highly unlikely for them to have any offensive intentions against the US; what business does a rebuilt Japan have to fight with the US? It's lost all of it's geo-political/strategic/economic incentives to do so, as the factors leading to a Japanese declaration of war on the US is gone entirely. On the other hand, given Germany's own ethnic issues and geographic proximity to the powers in question, the threat of any military build-up from newly formed satellite states goes up unless the Germans are confident of their control of those countries are puppets, which naturally predisposes them to be heavy-handed in their intervention in aforementioned countries' affairs, and thus increases the likelihood of built-up resentment against the Germans. For instance, take a decision to create a rump Poland: will that Poland remain eternally content with German overlordship and nominal independence (because that's what they'll get), when Germany (and Austria-Hungary) now hold territories with the greatest Polish minorities? Obviously, the Germans can only doubt that, and thus will try to keep them firmly aligned with German policy, which means economic support for Poland is unlikely; rather, they'll force Poland into an unequal/extractive economic relationship (particularly since Poland will have no choice but to trade with Germany/AH, due to a lack of actual ports) and exert heavy-handed interventions to keep Poland friendly, a move that will only antagonize it, thus forming a self-defeating spiral, similar to that which ultimately ejected the Soviet Union from Eastern Europe. Similar rationales are there for other states/territories Germany intends to peel off and either annex/vassalize, and to say nothing of Germany literally coming to dominate the entirety of Europe through conquest.
The German
Mitteleuropa project can similarly be seen in this lenses as being a means to economically dominate Europe. I can't imagine such an economic union being anything but a naked German attempt to dominate the economies and politics of Europe through it. While people make comparisons to the EU, it's fundamentally different, given how decidedly democratic and cooperative it is (at a state-level), even if some states (Germany, France) hold a greater share of the clout, and honestly, was designed originally to constrain Germany and prevent it from ever launching an aggressive war against its' neighbors again. Since then, it's moved away from that purpose, and the European project is something fascinating and leaves me hopeful, speaking from across the Atlantic, but I digress.
Mitteleuropa is only the means, in a CP WW1 victory, through which Germany can fully dominate the continent economically to the detriment of smaller European states.
Moreover, US foreign policy, despite many flaws, has always had an idealistic edge to it, one afforded by its isolation from any real competitors or threats after the Mexican-American war. The idea of American exceptionalism and that it's the "city on the hill" balances pragmatic power politics, and US foreign policy, though theoretically "high politics" and not constrained by popular opinion, is in reality quite held in check by Congress at the very least (if not the electorate), and democratic countries tend to be more risk adverse (
Democratic Peace Theory comes into play here). US motivations for the Marshall Plan were less about resource extraction (the US had no need for it), but more liberal (needing strong partner nations to trade with) and ideological (Democracy vs. Communism). The US was
ALREADY the economic superpower of the world, and instead of seeking to increase it's already significant hard power metrics (economics and military might), it took a softer approach to governance, relying on predominantly liberal institutions such as the IMF or the Bretton-Woods to build up goodwill and soft power, and taking a view of supporting Europe/the world against Communism, vs. dominating Europe for America's benefit.
In comparison, Germany's political system was an ailing hodgepodge of Bismarckian compromises that was barely creaking along, but was decidedly less democratic and liberal despite the growth of the socialists and liberals, as evidenced by them having no say in constraining German foreign policy and in effectively escalating and sparking WW1. Moreover, Wilhelmine Germany's foreign policy was just straight up terrible, self-encircling, and self-defeating. The Triple Entente did not form out of a conspiracy to destroy Germany (I mean, maybe France, but I'm pretty sure they'd satisfied with A-L and not worrying about the German juggernaut on their borders), but formed due to Germany's own deeply flawed bellicosity in foreign policy. Wilhelm's foreign policy blunders basically spawned the bipolar European alliance system, and thus the whole basis of WW1, really. Certainly, Germany's a revisionist power in the early 20th century and naturally seeks to build up stronger position in world affairs commensurate to it's hard power capabilities, but so is Russia, Italy, and Japan. Japan, at least, played it smart (well, until the 2nd Sino-Japanese War, then all sanity was thrown out the window).
Do you think a victorious Wilhelmine Germany will change from its aggressive expansionist and revisionist aims to a more liberal, cooperative one focused on soft power, particularly after a major victory that requires them to rely on hard power to maintain its new empire? That's rather unbelievable for me personally, and instead it seems more likely for them to double down on their policies.
A few facts to interject, although some have been alluded to.
Hindy and Ludy never staged a coup, they were the Silent Dictatorship and merely the most powerful of the power factions in late war Germany. The basis of their power was the 1851 Prussian Siege Law that gave Corp area commanders great latitude over the civilian economy etc, H & L used this and coordinated it centrally. When the war ends and demobilization occurs the Siege Law is no longer in effect and H & L will have to stage an actual military coup, which I seriously doubt they could pull off, so power will revert to the civilian government again.
Political liberalization had already been publicly promised by the Kaiser, in the form of changing the voting rules in Prussia the biggest state and where Imperial Secretaries were drawn from. This alone, and the example will surely be followed by other German states, would take most of the revolutionary heat out of Germany and ensure a 'normal' government postwar.
The treaty of Brest Litovsk was amended in August, after H & L moved west, to make the terms of reparations payments easier and weaken the language around Ukrainian independence. This is the sort of thing German politicians did when they took control of the peace in the absence of the Silent Dictatorship.
The Polish Strip was an essentially contested concept in the German halls of power. Ludy wanted the big strip, but the Kaiser directly 'your supreme warlord' asked Hoffmann and lil' Max suggested much smaller annexation, to get 2 or 3 railway stations (one was at Thorn) needed for mobilisation out of artillery range and Willy liked the idea. When Willy put this to Ludy Ludy yelled at Willy and laid down the law to him. However, as pointed out earlier once peace is declared Ludy will be shunted from power and its just as likely that Hoffmann's tiny annexations will be pursued rather than the big border strip, even if only our of spite by Willy for being disrespected by Ludy.
As is usually the case the devil is in the details.
1) While political liberalization was promised, typically governments are more wont to cede economic, domestic power over foreign policy. Unless the latter is firmly controlled by the liberals and socialists, it doesn't change how Germany governs it's new empire; and even then, the damage is probably still done given what happened in Belgium already, and the resentment already sown.
2) Ukraine and the other rump states formed by B-L were still used as puppets to extract wealth/value for the Germans (notably grain, which Germany understandably desperately needed), and changing that requires a paradigm shift in German foreign policy thinking.
tl;dr; while the liberals and socialists will get more power, I contest how much it would change German foreign policy, given the
Septemberprogramm was the blueprint supported by its economic and military elites.