Afghanistan had a big chunk of pro-Soviet citizens.
The American colonies had a big chunk of loyalists during the Revolutionary War.
It’s not so much the size of the dog in the fight, as the size of the fight in the dog. Russia is engendering deep hatred among many Ukrainians. Russian speakers in the (for now) “recognized Republics” are being unwillingly drafted for combat.
This invasion has also mobilized a new more serious spirit of resistance in Western Europe, and a strong appetite for a sustained proxy war among Eastern Europeans.
It is going to require long term fierce repression to control Ukraine after conquest - and likely continued strong repression and censorship in Russia as well. The Ukraine isn’t the only one being dragged back into the old Soviet Union, Russia is too. That prospect has changed Europe.
The number of pro-Soviet Afghans was small.
The number of pro-Russian Ukes % is almost exactly the same as pro-Brit Americans in 1776.