Signal is the world’s most widely used truly private messaging app, and our cryptographic technologies provide extra layers of privacy beyond the Signal app itself. Since launching in 2013, the Signal Protocol—our end-to-end encryption technology—has become the de facto standard for private commu...
If those “normies” aren’t turned away by the creation of an account (and if they can use Amazon, I doubt it’s an issue), they can certainly use XMPP :)
Here to pick a provider:
https://providers.xmpp.net/
Here for the software:
https://xmpp.org/software/?platform=android
https://xmpp.org/software/?platform=ios
Thanks!