I've been an android user for many years and so far I've been lucky enough not to need to have a phone repaired by a shop, so I'd never considered this problem until recently. I had to give my Galaxy S8 to a shop for repair. Since it's running Android 9.0 I thought I could use guest mode to keep my info private, but it turns out Samsung disables multiple accounts on the Galaxy. (WHY?!)
This is like handing the keys to the castle to a complete stranger. Having my phone with the lock screen unprotected is as good as having full access to my email accounts, my Google Drive repository, my social media accounts, and another dozen other apps with private data. Disabling them all and then reenabling them later would take almost as much time as just doing a factory reset and restore later.
Is there a reasonably simple way to give my phone to a repair person and have my data remain secure?