How does China pose a conventional military threat to Europe?

They don't. Dope is wrong again. Not that we don't need to arm-up fast. We need some more subs, and missile cruisers/destroyers, to keep in check Chinese ambitions within the SCS and Taiwan. But MBTs will be next to useless in any conflict with China.

Britain and Germany have both sent ships to the SCS. Australia and Japan have a HUGE interest, and cooperating with expanding their navies and naval exercises (I forget now the acronym for that alliance...I believe it also involves the UK and US).

As you say, it is to our benefit to continue equipping Ukraine to tie-up Russia. You are also correct that we need to counter the "belt and roads" initiative of China with one of our own. USAID, arguably, was a part of that. If nations can't get help from us, who are they going to turn to? (hint: China is very eager to make "friends" with them)

If we want to counter China, we are doing EXACTLY the wrong things, every step of the way. You would think that by random chance we would get one or two things right, but it's as if we are deliberately trying to cede power and influence to China.