Ordinarily I avoid this WWIII subject, but since the question is specific & limited, and actually is aimed at reality...
A POD that frequently comes up is a US/UK vs USSR war in 1945 over control of Europe. Normally the focus is on the US and USSR, with a bit on Britian, but if WWIII did break out in 1945, what could be expected of the rest of Western Europe?
Would France be in any position to rebuild their army, or contribute much? How about the low countries? Would the US and Britian be willing to use what is left of the German army, and if so what could they contribute? Could Italians be used in the war? How likely would Spain and Portugual be to join the Western allies?
France had eight or ten, depending on how they are counted, divisions with the latest US equipment and extensive combat experience. Another 8-10 were organized in France, but ill equipped. Those had a decent cadre of combat experienced and trained leaders. In theory the French could have organized at least thirty divisions with experienced/trained cadre. Equipping the balance from US depots would have required many months, so for the first months a dozen divisions would have been the limit for first class units.
Italy had a number of 'divisions' organized, but only a couple equipped and trained with US/Italian equipment. Actual strength was low for all.
Belgium and Netherlands each had some infantry battalions, & IIRC there was a mechanized brigade of Belgian soldiers.
Poland had one Armored Division in Germany and two infantry divisions in Italy. There probablly were other similar Polish formations among the western Allied forces but I cant recall details.
Brazil had two divisions in Italy. One just arriving IIRC
Denmark had several light infantry or military police battalions, organized and trained in Sweden, which landed in Demark on announcement of the German surrender.