I think you must first understand for yourself that Btrfs snapshots are NOT backups. They are a fallback for an update that breaks the system (as you already said above).
For real backups, you must have a backup policy/strategy that depends on your needs. Again, your text above shows that you already have one.
See them as two different things for two different purposes with no connection.
Strongly suggest to learn and use restic. It took me a bit to learn how it works, some time to test my backup strategy but now all my backups are done using restic.