This is the advice I find on other sites. Removing your account disables Factory Reset Protection.
Though someone else claims that “Erase All Data (Factory Reset)” from the Settings also turns off FRP, because you’re already logged in. And that what turns on FRP is stuff like holding buttons down to try and boot into recovery mode and reset the phone.
It’s not as bad as it was when I was doing phone tech-support for a living, but years ago, a metric ton of people never knew/wrote down their initial setup information. They’d never had an Apple or Google account before and had someone at the store (or a family member) set it up. So, for most of them, it was an ironclad bitch as anti-theft/security measures ratcheted up. And yeah, a lot of time they were having to do the account recovery (if they were LUCKY enough to have access to the account) and then wait before they could then complete everything and do the reset prior to trade-ins.
Not happy making for anyone, but, again, from experience, the sheer number of fraudulent phone sales (Craigslist was especially bad) or friend-of-friend deals was bad.
IMHO (very much so) the value of most older phones (unless it was a super-premium/rare model) is so low that other than some sort of super trade-in deal, that it’s almost never worth it with carriers - keep the phone as a spare or hand-me-down, because the problems with selling it online and the prices sold for are often just not worth the hassle.
I think it’s more to make it harder to reset stolen devices in order to resell them. That it discourages selling or gifting old phones is a (not unwelcome for anyone selling new phones) side effect.
I recently did this on a newish Android phone running the most recent version of the operating system. I don’t remember the exact details, but pretty much anything that requires entering the owner’s Google password to perform the reset will leave the phone ready to accept a new owner. I believe this can be removing the Google account first, and then doing a factory reset, or entering the password during the reset.
It was not difficult.
I know this is about Android, but a similar caveat probably applies to an issue I discovered recently resetting an Apple device. If the iCloud account a device is bound to has been deleted, then the device can never be setup with a new owner. Additionally, once the device is reset, it can never be setup with the old owner, because that account no longer exists. Fortunately this was an old iPad of minimal value.
So, don’t delete the Android’s owner’s Google account until after the phone is removed from their account.