Friend recognizes the right of self-determination for the people in Donbas, Crimea, etc. Friend somewhat counters this with the argument that while right of self determination is important, it isn’t worth tens or hundreds of thousands dying over. It’s worth adding friend is of a national subgroup with separatist ambitions and friend sympathizes with separatism, but makes the solidly materialist point that nationalism isn’t worth mass death.

On this point, the only answer is to agree - without a doubt, it was an incredibly terrible mistake for Ukraine to allow their explicitly Nazi militias to spend eight years targeting women and children with artillery, killing thousands of innocents. Russia took the initiative to stop this - if they want the death of innocents to end and the ones perpetrating the killing refuse to stop, well, someone has to step in and make them stop.

Friend also didn’t exactly agree but didn’t push back against the idea that Ukraine was hardly democratic, seemed to agree or at least not contest that bad actors have major influence in Ukraine, and agrees that Ukraine has a big problem with nationalism.

Ukraine was the most corrupt country in Europe before Russia invaded. It seems incredibly unlikely that they would have gotten any less corrupt, and likely have become even more corrupt.

I think the key disagreement I have with friend is that I think Putin honestly did seek some reasonable peace but the west stymied this, while friend seems to see Russia as the primary aggressor and that Putin isn’t really motivated by ideals of self-determination but is really motivated by revanchism and nationalism.

Your friend sounds like they simply don't know or understand that the conflict has been going on since 2014 and Putin made many attempts at peace, all of which were violated by Ukraine, not Russia.

Friend also expresses obvious disgust for sexual violence against women in the conflict and the targeting of civilian infrastructure, which is expressed as a reason to dislike Russia here so implicitly believes the sexual violence and is a problem for Russia and not Ukraine, and also because it is cities within Ukraine that are struck with missiles and destroyed and not really much significant targeting of Russian civilian infrastructure.

Again, you should remind or inform your friend that Ukraine had been using artillery to target schools, hospitals, and infrastructure for a decade before Russian forces rolled over the border. The "not much targeting of Russian infrastructure" is simply because Ukraine lacks the ability to do it - they've clearly made attempts with their piddly drone strikes. This is a limitation of weaponry, not intent.

Your friend sounds nice but quite ignorant about the conflict.

edit: The reality is, the average idealist liberal simply cannot be convinced by facts. They operate on vibes-based analysis. No amount of showing them the actual history of the conflict is going to make them suddenly realize America is evil, Ukraine is a pawn and America doesn't care how many slavs die, and Russia while not a shining beacon of leftism at least regards other slavs as humans.