The question remains, why Ukraine and not a more influential country first?
Ukraine is literally right next door, and was in the process of starting a genocide on Russia's border. That's significant.
And again, even assuming that what you said is true… Do you really, actually believe that this would be fighting against the nazis, not just fighting exclusively for the interest of Russian people? If those alleged nazi Ukrainians were killing Americans instead of Russians, Russia would do the same? It’s all about personal gain, there is nothing about fighting fascism here.
It's both, nations always act in their own interests. It's not a charity.
But do you believe Russia should have just stood idly by and let a genocide against ethnic Russians happen? Do you think they even could? Their own people demanded action, they had families in Ukraine that were in danger and needed Russian support.
There’s most of the western world supporting a genocidal Israel.
Worth noting, Russia is supporting Iran in their struggle against a genocidal Israel.