[rl3]

It was never an issue for me. Giving the SimpleSSHD docs a quick glance, the app itself does not operate as root, although its packaged subcomponents like rsync optionally can depending on what shell you point them to.

My phone isn't rooted. Everything in /storage/emulated/0 backs up without issue. Obviously not a full system backup, but all my data none the less.

With regards to write permission, I've only ever issued any writes to my image folders to prune photos or screenshots older than xx days that have already been backed up. On that note, freeing up 20GB of space instantly with a single command is incredibly satisfying (compared to the MTP hell alternative).

[CapacitorSet]

If you only need a shell, adb does that, as well as blazing fast file transfer (for the standards of MTP).

[rl3]

For sure, although I think it isn't as well suited to being a remote daemon. With SimpleSSHD, all concerns are compartmentalized into an app, you get rsync out of the box plus a nice minimalist UI for monitoring. Then adb can be left disabled, and its configuration untouched.