Cloud Storage Provider with file handles

Is there a cloud storage provider that provides file handles similarly to CIFS/SMB? We are using Dropbox and we would like to receive a warning when a file is opened by someone else (if there's a conflict it just creates a backup file). We don't like the solution where you manually lock files/folders with an interaction menu that Dropbox Business allows us to do. On the other side, we really enjoy the performance improvement from local caching with Dropbox!

We used to use a NAS via SMB in our local network, which supported this. But with a migration to remote work, this is no longer an option as the bandwidth of our office is not sufficient.