If it is WebDAV, DAVx5 has a feature that makes those shares available as a local volume. An sFTP app can be used to xfer files.
TrueNAS probably has a service for synchronized folders like google drive. I don’t know how to access NFS or SMB transparently.
Yep, it’s that easy. I have it on my pixel 2xl, degoogled and it’s still usable {android 14)