I think there's like three groupings of pro-war Ukrainians. First, speculatively, is the "Hey, Russia invaded our fucking country not cool bro!". I can't prove that this group exists but it seems reasonable to assume that there are Ukrainians with a reasonable degree of patriotism who aren't hard-line nationalists. "I'm just defending my home" type people.

Two is Right-Wing Ukrainian Nationalists who want to forcibly suppress the Russian language and the Ethnic Russian Ukrainian Minority. This is a big group, Western Ukraine seems very nationalist and the snapping point of the Euromaidan coup was, as near as I can tell, Ethnic Russian radicals in Donbas recognizing that the new government was made up of hardliner Ukrainian Nationalists who were going to strengthen Kiev by suppressing the Russian ethnic minority.

And then the third group is actual Nazis and Right wing radicals who are not meaningfully different from Nazis. These are the guys that Kiev sent in to the Donbas to suppress the uprising during the "Anti-Terrorism Operation" preceding the Russian Invasion. They're the hatchetmen for the relatively more moderate Nationalists, the guys the Nationalists call out to do their dirty work. They were deployed because they were the only organized groups that could be readily mobilized in2014, as the Ukrainian Army were a shambles and the Ukrainian police/security forces weren't able to restore order.

I think the government is almost entirely Ukrainian Nationalists, and has become more so as the civil war progressed and moderating voices were pushed in to exile or hiding. Deploying Nazis against their own countrymen seems to have strengthened the resolve of the Donbas factions, as well as increasing public support for them; People saw that their own government had unleashed Nazi thugs against them and turned against an already unpopular Kiev government. As the low-intensity civl war progressed things became more and more polarized, and as we know the Nazi fringe constantly violated cease fires and frustrated any attempts at a negotiated peace.

I really do wonder what the RF's commanders thought was going to happen that made them trigger the invasion. From what I understand Ukraine was massing for a serious offensive in to the Donbas, and it seems credible that protecting the Russian minority was one factor in choosing to invade. They also have territorial aims, and I suspect the Russian leadership doesn't have any respect for Ukrainian Nationalism or the Ukrainian state, viewing it as simply an administrative mistake caused by the chaos of the breakup of the USSR. I wouldn't be surprised if they originally had a goal of militarily defeating the Ukrainian army to de-militarize Ukraine and remove the nationalist threat on their border, and eventually it became clear that they wouldn't be leaving any time soon and chose to dig-in and make it a permanent arrangement.

I don't have any love for Russia or Putin, but their actions seem rational enough. I thought the "Special Operation" moniker was just propaganda newspeak, but as I've learned that Russia has only mobilized a very limited part of it's military and wouldn't be able to mobilize the full armed forces unless Ukraine invades Russian territory, the distinction makes a little more sense. It's not quite like the US saying that Vietnam was a "police action" while it mobilized the entire US army and flattened the country, this really is a limited military intervention with limited aims and a great deal of restraint relative to a full military mobilization.