First of all how do one have access to the seed of core lightning? And how the backup of core lightning works?
Honestly, I’d use the built-in umbrelOS Backups rather than trying to back up Core Lightning manually. Go to Settings > Backups and configure a destination. Umbrel will then automatically make encrypted backups that include the Core Lightning recovery data.
The manual methods involve handling sensitive files and following CLN’s recovery process exactly, so they’re pretty technical and easy to get wrong. umbrelOS Backups is the much simpler option for most users.