The backup key is shown the first time you enable encryption.

I guess they've changed this in the last 2 years or so because last time I checked they kept your key hostage and only allowed transferring all data, including the key, to a new phone.

I'm using this method since 2020 or even before. I've never ever enabled the backup on GDrive.

Is your phone rooted?

No, it isn't.

Would you happen to have good resources detailing the process?

Pretty much what I summarized back in 2019: https://scarpino.dev/posts/automated-phone-backup-with-synct...

Nowayadays Syncthing is no more maintained due to some PlayStore drama, but Syncthing-Fork is a good replacement.

Thank you for this. Just adding this here:

There seems to be an issue with recent Android apis that make file access painfully slow that it wasn't able to sync my data in 1 full day. Enabling the "Case Sensitive FS" option on the folder helped a lot.

https://github.com/Catfriend1/syncthing-android/issues/1088#...

I'll start from there, thanks!