Ukraine will fall to Russia and, from within that reality, Ukraine will be fighting Russia to get out of their country for years to come. But, the pockets of resistance will get smaller year after year until Ukraine fades into the history books. We and others in the West will be very mouthy about it all but, in the end, Ukraine will be gone and Putin will be left with black eyes which may never heal.
Taiwan is a different animal. We have no hope of defending Taiwan, even in the losing way we are trying to fight for Ukraine, unless we're talking about all out war with China, in which case, Russia, North Korea, and Iran will join China in the fight against us. It will be WWIII and it will wind up being nuclear. As Putin recently admitted, no one wins a nuclear war. Once again, the only thing we can do for Taiwan is to let them fall and be very mouthy about it. China won't even allow anyone in the world to send Taiwan future arms to defend themselves. China will be able to effectively blockade any and all arms from reaching Taiwan.