It’s important to remember that Chinese leadership have explicitly said in the past that they will wait decades if need be to peacefully annex Taiwan.

They've said that in the past, but that's not what they've been saying recently. They've subtly changed their rhetoric on Taiwan in the Chinese internet, basically getting the population prepared for the possibility, in accordance with the DPP and the US moving rhetorically closer to independence. Hopefully the DPP aren't as crazy as the Maidan Ukrainian nationalists.

tbf Russia is responding to an escalation in shelling in the autonomous regions, but this is way beyond the expected response. I wonder what Putin intends for the end outcome to be. Surely not the annexation of the whole country, so perhaps setting up a puppet state so it would stop needing to deal with the government the US propped up?

I'm hoping that the end game is to go in, kill and capture a lot of Azov/Right Sector people, disable the Ukrainian military, and then get out, while laying the groundwork to annex DPR/LPR. They might not feel that they need to do anything else after that, because Ukraine will have lost a quarter of its territory, the Maidan project will be basically dead, and Ukraine itself might crack up. I think they're gambling that after this, most Ukrainians will decide that following the hard line nationalist path simply isn't worth it. I'm hoping this is the case, but who knows what could happen. I couldn't imagine Russia would really do this before, and I can't know what their endgame is now.