I don’t know anything about iOS, but I use FB on Android for the marketplace. I keep a prepaid sim card for giving a phone number to accounts like this. I throw away the sim every few years and burn the accounts and make new ones. FB is used from a browser in a seperate work profile on the phone to keep it isolated.

This sub obviously has a strong reaction against FB. But if you need to use it then put up what defended you can and go for it.