They understand why I am passionate about selfhosting and privacy but they still have a reasonable expectation that things just work.

That’s somewhat where my head is at too at the moment. I do want to go the privacy route but I do also want something where it can “just work” (hence why I’m looking closely at third party solutions like entee and filen or proton drive). I do care about privacy, but having all the creature comforts that companies like Google has provided is still a bit difficult to let go.

Sync will stop once I close the app.

This is an iOS limitation, so no going around that unfortunately.