So, what would Portugal do and look like in the postwar decades? Could the Portuguese monarchy be still saved with a POD in early 1900s? And how would Portuguese neutrality in WW1 affect their internal situation? Are there any credible alternatives to the PRP-controlled First Republic and later dictatorships?
This is the world we're talking about, to cut the long story short:
POD comes around roughly at the time of the First Moroccan Crisis. Relations between the political and military leadership of Germany improve a little, while the focus of military spending is gradually turned to favour the army at he expense of navy, after the German diplomats manage to secure an Anglo-German Naval Treaty with Britain.
Later on, starting from roughly around the time of OTL WW1, Germany and Austria-Hungary fight against Serbia, France and Russia, with the Germans focusing to the Eastern Front and leaving Belgium alone while standing on the defensive in Alsace-Lorraine. Britain, being uneasy to see the conflict threaten the status quo that favours them, is temporarily distracted by the violence in Ireland due the Home Rule Crisis, but nevertheless gears up for war and starts to pressure the Central Powers to end the conflict.
Germans, with their war effort led by von Falkenhayn and political leadership more in step with reality than in OTL, are happy to offer Russians terms after a revolution in the country forces Nicholas II to abdicate and turns the former empire into Russian Republic led by shaky coalition of Mensheviks, SRs and Kadets. Loss of most of Russian Poland and the Baltic provinces (including Finland) is a harsh deal, but with their sole remaining ally bogged down in the trenches of Western Front and their internal situation volatile, the Russian government led by Grigory Gershuni ultimately agrees on the terms on autumn 1917. Following this the British diplomatic pressure and covert threats of intervening to the conflict on the side of France force the war-weary combatants to the negotiation table. While their European borders remain virtually unchanged from pre-war status quo due British insistence, France still loses Djibouti, their rights in Morocco, Guangzhouwan Concession from southern China and some territory in Congo and Camerun to Germany. While outright revolution is averted, the bitter result of the bloody conflict still causes great upheaval in the French society.
In the postwar years Germany is busy organizing their new Baltic puppets (United Baltic Duchy and Kingdom of Finland) and arguing with Austria-Hungary about their joint rights in the Kingdom of Poland (ruled by a Hapsburg and mostly controlled from Vienna - the TTL Austro-Hungarian war effort was much more succesfull than in OTL and captured large parts of Russian Poland in 1914)