As of the time I’m writing this comment literally none of the suggestions made actually matter for the ambiguous goal of “general security and privacy” more than building in a neighborhood or community that meets the occupants desires.
Pick a place with people you want to be around who you trust to look out for you.
People will dislike this:
The most basic one with little barrier to entry is imessage. Theres a good chance your friends and family already have it and with a few setting changes (no sms fallback, set icloud recovery key, probably some stuff I forgot) you’re damn near at parity with signal.
All without dad having to download a new app onto his phone and make a new identity!
Of course you’ll need signal or something for people who don’t use it.
I use that combination and it’s excellent. If you can be on imessage with someone you’re good and everything works, if not you do signal.
There will be people you gotta use sms with. They just won’t be able or willing to do something new. Sometimes there’s an equipment problem, their super old provider version of android can’t get an app you both agree on. Sometimes they’re using a Nokia.
Interacting with sms often may help keep you on your toes about it. I know I’m more careful over text now.
That combination, imessage and signal, also has a benefit of reducing the chances that you’ll broadcast an awareness of and desire for privacy and security to the whole world all the time.
In the us, there’s a 50% chance you just look like a normal person and that’s nothing to sneeze at.
Make sure it meets your needs of course