If they choose to keep fighting

1. How may of them chose to fight in the first place, aside from the neo-Nazi ones? Many of them were conscripted and forced to fight.
2. How many of the women & children & old men want the fighting to continue? The Ukrainian government is a shit government; how committed even are they to its survival? This is a post-US coup government that has banned opposition parties and is auctioning the country off to foreign capitalists. All of the aid they’re getting is lend-lease, which they will be repaying for generations. This is going to be full-on neoliberal shock therapy.
3. To what extent does the Ukrainian government have a choice in whether to continue fighting, when the US clearly has a lot of say in the matter despite its claims to the contrary?

A pretty fair point but I still think you are neglecting a few things.

Firstly, while according to this study by the Kiev international institute of sociology most Ukrainians do still support the war it also indicate that the portion that peace at the cost of losing territory is definitely growing since the start of 2023, if I were to try giving admittedly loose and uncertain bound based on those numbers and assuming the rate of change don't shrink, I would expect this portion to reach 50% of the population 2 months from now at the soonest, 11 months from now at the latest.

An other related thing to consider is how accurately is the state of the war depicted in Ukrainian media? A state at war that don't plan to surrender has incentives to make their war effort as good as possible and the enemy's war effort as bad as possible and Ukraine is obviously no exception.

Depending on how distorted the narrative about the war is, these figures could be drastically different from what they would be if the Ukrainian public got a more neutral account of the war.

So do the Ukrainian want to continue fighting? For now yes, but I don't believe it will last.

Your leverage point is moot in my opinion.

As I said, it is a fact that Russia is winning the war and that Ukraine has decisively failed to push them back before the Russian entrenchment in their position and the dwindling military supply to Ukraine made doing so impossible going forward.

I'm not saying that Russia could just roll over to Kiev any day if they wanted, that would obviously be absurd, but the military situation in Ukraine, the state of western weapon manufacturing compared to Russia's and the sheer difference in manpower reserve and moral make it such that even if the west threw every last weapon in their stockpile at Ukraine, it would not change significantly what a peace deal between Moscow and Kiev could look like. I repeat therefor once again that the ONLY thing continuing to supply Ukraine with weapons is increasing the death toll on both side and prolonging the was for nothing, it's literally not doing anything more, let alone helping Ukraine in any tangible way.

You are right, though, that most of the aid to Ukraine is humanitarian and not military, and those absolutely should continue, but that's one reason more to not prolong the war uselessly, the end of the war would make helping the Ukrainian people way easier and would allow Ukraine to start rebuilding.

Well as per the article that choice is clearly not theirs, it's the United States'. And the US says war

The same way they did in 2014. Don't worry, the US is very used to this (and this is just from a NATOpedia article).

In this scenario, by assuring the coup plotters that the U.S. will keep funding the war as long as they keep fighting it, as opposed to cutting bait with the coup as an excuse. The coup plotters would then accuse the deposed government of treasonously planning a surrender (a mischaracterization, but that's par for the course) and portray themselves as acting in the national interest. They then keep the status quo of the war, with just a change in management. This would all fit neatly with the anti-Russia/pro-U.S. propaganda Ukraine has been subjected to. Any Russian objection would be written off as lies.

If Russia tried to support a coup government, that government would be branded as treasonous even if they sought to act in the best interest of the Ukrainian people. The U.S. would immediately seek to discredit and destabilize the coup government, and a lot of Ukrainians would listen as they're fighting a war with Russia.

Zelensky just removed Zaluzhny from heading the military because Zaluzhny was getting too popular and becoming a political threat. Important to point out that Zelensky has called off the elections that should be happening right now and that there's growing dissent for his administration due to how poorly the war is going. Also worth pointing out that Zaluzhny has ties to the far right militias of the Ukrainian armed forces and flaunted this fact when Zelensky first tried to have him removed. It would be very easy for NATO to back Zaluzhny and his right wing thugs (the same ones that took part in the maidan coup) against Zelensky if Zelensky breaks with the West's wishes. US intelligence agencies are very good at pulling at threads of existing dissent to create chaos and oust difficult political leaders