GrouchyGrape while I understand your position, I wish I had a dislike button for this.
"Use your app's backup feature" is frankly not a very appropriate answer to a very long and well reasoned post. Leslie knows that and, likely frustrated, uses for the lack of the better option.
But this solves none of the original issues, only permitting some extent of some data security, but nothing for the vast majority of the apps and suggesting to just use apps that offer it is.... well, it's a bad answer. If you need to hear why, it's because (1) not everyone has a choice of only using a several, carefully chosen compliant apps, (2) the apps that offer data export/backup don't always back up everything, (3) this sort of backup is almost always manual, resulting in the lack of backup.
I cannot possibly imagine going through all my profiles, skipping some very important apps that don't do backups, opening all the remaining apps, searching for the backup procedure, different for every app (and handling dozens of backup passwords), initiating the backup, finding the backup file, copying it to pendrive.....
Seriously, this is not a solution. This is not even a workaround. This is good for when someone's moving an app, a single app, between phones/profiles.
For all intents and purposes GOS doesn't have backup at all (because whatever we have now gives nondeterministic results with every run, which means it cannot be trusted, because every single backup would have to be fully restored and verified to be considered successful).
And that's no longer tenable at this stage I think.