WhatsApp can never secure our messages because it is not libre software, so we do not control it. Both are trash but at least WhatsApp uses the internet instead of directly costing money like SMS.
Oh, that’s a good start. Teach them about libre software and show them F-Droid. PipePipe works better than NewPipe and you can get it there too. Good luck!
You don't know the S in HTTPS?