Cloudflare tunnels are layer 7, so it's not unlimited access by any means. This also means that certain things will break btw, for example if your website uses websockets to load information, that isn't supported.
Next, I'd put the computer that is going to be hosting into an isolated vlan of its own and access via external URL only.
If you're going to use docker images, make sure to vet that they're updated often and always spin up the latest.
That document doesn't say what layer. But it does say it supports Websockets.
Just odd that when I try to set it up using a named tunnel I don't get an option to specify the WS service type. However it does require a service type if you want to connect to it.
Looking at this page it would seem that it's a layer 7. Although I could be wrong, but my front end app has issues finding my backend service for websockets.
Granted I even tried to connect to my private computer using other protocols. I couldn't get through. Anyway I'm most likely going to be taking that project offline soon.