Tweaking a couple settings is a pretty tame way to fight Meta.

Organise a move from Meta/FB/Insta to the fediverse together with your folks, and close the accounts. This way you don’t loose important contacts during the move, and Meta loose more users.

First impression: why another messaging system?

It may be fine, but what does it bring that Signal/Briar/Matrix/XMPP+Omemo doesn’t have? Does it use existing standard protocol or encryption that’s compatible with other messengers, to avoid fragmentation?