The Nazis in Ukraine aren't just emboldened by the state, but in control of it. Russia is governed by nationalists, not by Nazis. Ukraine isn't simply using Nazis to further their aims, but the west is using Ukrainian Nazis to further their aims.
Russia is not imperialist. It has a paltry amount of finance capital, and no colonies nor neo-colonies. Its status as a capitalist nation no longer imperialized by the west like they were in the 90s strategically aligns then with the global south. This is why, say, the Sahel States turned to Russia for support in their national revolution against imperialism. Russia doesn't participate in unequal exchange, it doesn't keep tech monopoly nor does it undermine global south development.

I'm not doing imperialist apologia, you're incorrectly identifying this as an inter-imperialist proxy war and as a consequence misanalyze the situation. This is why reading theory and studying the class components of the states involved, and their positions in world imperialism, are necessary.