For me: uploading single file using their client ~25MB/s, downloading ~50MB/s (30-60MB/s).
In newer versions of their linux client it's possible to mount filen as network drive or to start webdav/s3 server.
It depends if your reverse proxy is inside your home network or outside. It should work without any other configuration if you forward ports 80&443 from external domain with something similar to rathole and configure reverse proxy inside home network.
Have you tried syncthing? It works great with keepassxc.
Vaultwarden is pretty easy to self host.