If you will be using roaming for mobile data in China, you won't face any blocking.
Accessing over cloudflare tunnels or just a normal exposed server works.
VPNs work most of the time. But you can be cut off after like 30 minutes to an hour. I'd recommend only turning it on when you need it.
I've been to China very recently.
You will most likely face speed issues, although this may be due to the physical infrastructure itself connecting China to the outside internet isn't really that stellar. As everything Chinese citizens typically use is hosted in China.