Isn't SMB not recommended because it can lead to corrupted database? Or is there a setting I disabled somewhere in my smbd.conf that I should re-enable (oplocks maybe?? )?
Since only a single process may write to a database, it would be best if that process were local.
NFSv4 has built-in file locking, which is likely the most preferable protocol. SMBv2 is a massive rewrite of that protocol, and I expect any file locking problems would be addressed (especially as Microsoft sponsored SQLite changes specifically for Windows 10).
Remote readers in explicit read-only mode likely won't hurt, but there is a deeper discussion below.