Ukrainians certainly can, but you can't ignore the fact that a lot of NATO's motivations for helping isn't just altruism. Part of this is also the proxy war being fought, and even if India and China want Ukraine to win, they may not want to be the ones paying for a NATO victory.
Small wars almost always drag in bigger powers.
But that doesn't change much. The US intervened in Vietnam and Afghanistan and because the locals didn't want them, the US still lost.
Foreign contributions in Ukraine pale in comparison to Vietnam and Afghanistan yet Ukraine is resisting. And this a full blown Russian invasion, not just a Ukrainian civil war, yet Ukraine might even win this war.
That's strictly the merit of the Ukrainians. You can gift weapons, but not the will to fight.
Ukrainians have the right to decide what they want to do and what, if anything, to give up.