It's easier to convince them if you don't have Facebook to begin with. Then it can't be used as an excuse. Nearly all my close friends and family have Signal.

As for shitty photos... they can see them on the TV when they visit :)

I have considered making a pseudonym account just for Tinder though (hi ladies!)...but greeting people with "my name isn't actually Johnny Depp" does not sound like the best opener either.