Is backing up data folder of Linux desktop app enough?

I have the desktop application installed and running at all times. I do a full incremental backup of my system once a day. Would this be enough to backup my Bitwarden vault if the data folder in my home directory (The folder with the data.json in it) is included in the backup?

It so, would I be able to put this data in to a new, different Bitwarden account? Would I be able to import it in to a self-hosted vault? Would this be a more complete backup than just exporting the .json manually, or is it the same?

Definitely not; the best way to backup your vault is password protected export.
see this link for more details:

just copy your bitwarden client data directory is not a reliable backup.