The Ukrainians are not being forced to fight. They are doing so (at a national level) of their own free will. Obviously they would not be able to do it without our support, but that doesn't change the fact that the United States is not forcing Ukraine into fighting for longer.
So when people start talking about the morality of throwing Ukrainian bodies into the meat grinder, I find it curious that they do not consider the Ukrainian point of view on whether it is a worthwhile loss of life to resist Russia. Personally, I trust the Ukrainian perspective on whether you Ukrainian lives are worth resisting Russia. Certainly more so than I trust the opinion of Americans who, while many of us have served our country and suffered for it, none of us have been even remotely close to living under an authoritarian boot. The Ukrainian memory goes back a while.
I said from the start that I believe the concept of sovereignty is vital in both the moral sense and in preserving some sort of global stability. So I'm inclined to support any country that is in a war of sovereignty, which Ukraine very much is. Arguing about Russian borders from before the Cold war seems silly and irrelevant to me, as the USSR waged a decades long war to build their empire and lost. Losing the western territories was part of that loss. There is no allowance to the concept of sovereignty for historical borders.
I also do not believe as many populist republicans seem to believe that there is a world where we can isolate and avoid conflict. I see the coming storm as inevitable, and given the opportunity to annihilate the fighting forces of one of the most likely major adversaries in the coming conflict, I say we take it. Again, I would not support expending American lives to do so, and I certainly wouldn't support forcing the Ukrainians to expend their lives, but so long as they are willing, I believe the cost is worth it. When you compare that cost to the other things we are deficit spending on, it might be the greatest deal in the history of Fiat currency. What better way to spend made up money?
Would I support the same action against China? You betcha. If China wants to try to invade another country, and that country can bleed their military out using our intelligence and weaponry, and the people of that country are willing to fight, it's a no-brainer. Taking two geopolitical adversaries off the board before our economic death spiral starts to seriously impact our ability to project global power would be an incredible advantage going into the fourth turning.
I think part of the key difference is that the populist conservative movement (best exemplified by Tucker Carlson) seems to believe that there is an option for some sort of perpetual status quo going forward, if only we don't rock the boat too hard. I disagree emphatically with that belief. History moves in waves, and just like real waves, trying to stop them is pointless, and potentially fatal. Move with them, even try to ride them, and you might end up on top. Might.