You can probably use `adb backup` (described here: https://www.technipages.com/how-to-backup-your-entire-androi...), then extract the backup using `android-backup-extractor`: https://github.com/nelenkov/android-backup-extractor.
I've seen some people advocate replacing the installed version with an older one which does allow backups (by uninstall and reinstall, hoping the uninstall can be done in such a way as to not delete the app data) then use ADB backup on that one and reupgrade before launching it, but honestly it's easier to backup, restore on a rooted phone, extract the key, then restore again on the unrooted phone to get service back (the key doesn't change afaik).
You can do this on a different phone without messing about with SIM swapping etc, you just need access to receive SMS messages on the number the backup is tied to.