I mean, obviously Ukraine won't. Does that need saying? It's insane to think about. Look at the history of WW1 and WW2: Russia will fight until the Russian state collapses and we're, at minimum, years away from that happening. And Ukraine, if they have any sense whatsoever, will do exactly very little for anyone else until that happens. Only a German dictator is stupid enough to answer "What do you do if you're stuck in a land war with Russia?" with "open 3 extra fronts" and we all know what happened to him. Ukraine is fighting from the underdog position and that means: no stupidity. And that means: no fighting China, no defending Taiwan, even despite the fact that China is fighting Ukraine. Sorry.
Europe and Canada utterly depend on China in 1000 different ways. They have chosen not to defend anyone, and will need a decade (minimum) to rearm. And even rearmed ... will they be able to challenge China? At that distance? Other than France none of these countries currently have the ability to project power outside of their borders at all, so they will do exactly nothing, because they've chosen to be utterly powerless (google "the peace dividend")
These countries are actually smug about those decisions, despite how stupid they are. I was recently in Ireland, and in a pub I found that that NOT ONLY Irish people were proud NOT to support Ukraine, but they were "proud" (their words, not mine) that they were still supporting Russia, because that matters to them personally (ie. jobs from Alumia exports and cheap Russian gas for everyone)
You know, people kept screaming the same thing with the USAID cuts. Everyone else will take over and get goodwill from everywhere instead of US. Reality then was that nobody took over, and where they did, it was to support armies, not people (e.g. UAE "helping" Sudan, Russia "helping" Mali, ... of course all of that happened with UN approval or at least silence)
Reality here is that if the US doesn't help defending Taiwan, nobody will. Not even Japan or South Korea. MAYBE Taiwan will get Ukraine-style loans, if that even matters (without US help, China will be able to fully control both sea and air routes into Taiwan in a matter of days. So even if Taiwan has money to spend, delivery of anything they buy will be utterly impossible)