I have been pondering this for some time in parallel to you, and others, it seems. My POD(s) are different but here are some things I came up with that you are free to use, ignore, think more on or whatever you like.
The USA never gets beyond a hostile neutral with respect to Germany, British efforts to embargo/blockage Germany only add friction to Anglo-American relations, this divide deepens as the British turn towards protectionism post-war and focus on the Empire (Commonwealth). Entente rejection of Wilsonian (holding place for the concept) peace overtures and German willingness to seek peace beginning around 1916 create wedge in American relations with Entente driven home by Entente "recalcitrance" post-war. As America seeks to rebuild trade and German needs trade the two grow closer, not snuggly, but the slippery slope tilts here.
Germany sees the SDP take power with Zentrum and a break away left leaning Liberal faction, still vaguely led by Zentrum since the Socialists likely are not full ready to spread their wings or hold a true majority. But I think one sees a lot of political battles as the same issues in OTL get addressed, lower the voting age, women's suffrage, expand the welfare state, deal with wounded veterans, unemployment, war debt, and so on.
USSR born but has harder time of it, might retake Ukraine but Poland and Baltic states stay out of their grasp along with Finland. Once politicians and diplomats reassert authority over Army the situation in East tones down from naked occupation to better relations. I see more instability in Poland and German restrained by its pursuit of peace with Entente so Poland likely suffers a civil war if Soviets can pour fuel into the nationalist sentiments. This might be the icebreaker to German reintegration with Europe or sets off another war. If former it sours everyone to USSR at minimum. Maybe Japan seizing more territory from Russia in Far East and maybe creating a Russian "Manchuria" puppet.
Germany negotiates for return of colonies in Africa and Pacific, UK agrees in the 1930s akin to the appeasement years. Japan holds out and this drives wedge into German-Japanese relations, pushing Germany and China into better relationship. Here the UK and Japan are still friendly on surface but the relationship is rotting, mostly due to Japan asserting itself in China, but without WNT the USA never gets friendly with UK in the Pacific. Sino-Japanese War still possible. But war with USA and Colonial powers less likely. I see Germany supporting China akin to how it otherwise happened in Spanish Civil War.
No Spanish Civil War. I can still tease Italy into Fascism and its relations with Germany are frosty, as regards Austria they are bitter enemies. The UK with France prop up Italy and we still get the path towards an Italo-Abyssinian war. Fascism lasts longer.
No Holocaust, in fact Germany improves its assimilation of Jews based on their service in the War, anti-Semitism gets a cold shower of impropriety, longer term . Jewish minorities in other places might still see discrimination and persecution. Zionism remains a minor voice, possibly no Palestine, almost certainly no Israel. But likely still an Armenian Genocide, with a surviving Ottoman Empire and German Empire I could see this getting more directly faced, I think it does not fall into the cracks of history.
Germany's SDP led governments pursue a far more liberal policy in the colonies to become "models" of progress, it also serves to twist the tails of both Britain and France, anti-colonialism is driven more by outside forces, opening markets becomes the goal, revolutions sponsored by the USSR and independence sponsored by the USA and Germany and Japan.
The British Empire fares better overall, Indian independence occurs but not necessarily easier or better. Once India goes the Empire begins to unravel. Focus in Asia likely goes to Malaya and Singapore, more attention to Africa maybe, but I can see the British having more sway in Persia and more troubles, this sets up the UK versus USA for dominance of global oil. Germany might become the big player in Mesopotamia, possible USA partnership, especially where the Ottomans push back to reassert control over the Arabian peninsula. Another flashpoint for war. No dominance of Wahhabism in Arabia, over the Holy Cities or in Islam. The Caliph in Istanbul potentially develops more authority over Islam internationally.
France alternates between its leftist and its right wing, deepened by the decolonialization wars, especially in Indochina and Algeria, the Nationalist Chinese begin supporting Vietnamese nationalists and Italy supports Algerian separatism, same messes, different actors. Franco-German relations remain frosty longer but economics might drive them to better times. I am open to a plebiscite in Lorraine, if so then maybe the French refocus on becoming a bigger player in European markets and evolve towards becoming Germany's biggest trade partner as tensions fade.
The USA never becomes a global superpower, it likely remains a major naval power and its bigger contribution is in civil aviation. Otherwise no CIA, no Cold War, no global posturing versus the USSR. The USSR becomes a dangerous power but also not superpower status. If it fails to take the Ukraine or loses ground in the Far East it might barely register other than in Germany's worries. The world evolves in a multilateral structure akin to the familiar Great Power game.
Technology? I see airships through the 1920s, the USA agrees to sell helium and Goodyear partners with Zeppelin. The USA leads into aircraft like the Constellation, Germany legs as it leads in military aerospace, but has a strong second place, followed by the British who do better (I hope). Germany has a sort of cold war with the USSR and maybe the former Entente so it still leads in military technology generally. The Germans get similar trade with USA but less with France and UK, but those remain closed to German trade and prefer their own longer. Very outside chance that rocketry gets as far, Germany might innovate versus pursuing long range bombers but then it has no need to fly further than Moscow. So satellites might be long delayed. I think we see more German players in trade, Japan might not get the big take off, worst case it sort of stagnates into a military dictatorship for a lot of years. No Walkman. China looks similar to now but with petty politics in factious parties, democracy after a long one-party state under the KMT, then liberalization.
That is my broad strokes to play with themes, not always diligent in letting butterflies change everything.
For background my ending to the Great War is currently a stalemate, the Armistice is just that, rather akin to how the Korean War "ended". With much still left open, I am pondering the CPs holding on as a bloc with the USA and USSR as the "non-aligned" other powers who lean towards the Entente and CP respectively. The British never warm to the Soviets and the Germans fail to support the Whites as Lenin steers towards peace with the CP, the French are less desperate but still bled dry. The 1920s are less about disarmament but the costs of war still force a peace, treaties get settled as we get later 1920s or 1930s, more like how World War Two was finally ended.
