You do not need to shut down services to make snapshots, why would you?

I won’t use fs snapsots as backups especially one as poorly supported on linux as zfs. I would go with external qcow disk snapshots and they can be pretty easily automated.

Don’t fret about ssd lifespan, unless you are planning on writing tb a day they will outlive your setup. I wouldn’t personally use zfs for this, unless you have a lot of memory just laying around.

Well if ika1988 says so.

That was not about root access, but full access to hardware features.

Depends, if it can do everything that termux does without some kind of security features that will make it unusable it can prolong device life and phones have a lot of different things in them including great cameras!

Great! This is a list I was looking for, due to my phone slowly dying.