The presence of Neo-Nazis within a nation's borders does not give another country just cause to invade unilaterally. The idea that, because Ukraine has Neo Nazis and incorporated groups like Azov into its formal military structure, it makes the Russian invasion justified, is to implicitly accept that bigger, more powerful countries are entitled to "spheres of influence" and thus should be able to unilaterally intervene in their neighbour's politics when it suits them.

Ukrainians aren't particularly more supportive of Neo-Nazis than any other white-dominant nation in Europe – it was just an excuse by Russia to invade.

What kind of evidence is that? There are neonazis in every country, that of course does not mean refering to a whole country as "fucking Nazis"