One of the things I miss about social media (after not having been on Facebook for a good number of years now) is the convenient mechanism for communicating with friends, family, and acquaintances. The trade though isn't worth it for me -- my attention being used to fuel algorithms for targeting advertising with the side effect of amplifying messaging that I rather not have occupying my psyche. I haven't completely distanced myself from social media though -- I still use Twitter mostly to follow folks that challenge my perspective and augment my frame of mind.
For a while I used Keybase but phones and a laptop later I've kept forgetting to actually use it for messaging. Unfortunately I've been locked out of my account and I'm waiting for a reset to happen. I used to have a WhatsApp account but I didn't find much traction with that in my family nor acquaintances. Not having Facebook (as I've deleted my account) made it extra hard to be involved in group messaging in the past year. There's other solutions like Slack for the communities I belong to and Discord for the folks I play D&D regularly with, but that's different from a secure way of reaching folks with verified identities. There's Signal which is an interesting way of doing it which may be my preferred approach.
This is becoming important because I'd like to be able to solicit feedback from some early writing I'm doing, and would like to keep it secure in transit and with groups of folks. I'm big into using public key cryptography (my public key fingerprint is "FA91 CAC8 8A7F 7785 205A 5B31 0463 F512 E8EF 2E5B") and if you wanted to reach me securely, encrypted email works great. The initial investment of being familiar with and creating your public and private PGP keys will allow for more trust-worthy communication that's end-to-end encrypted. Using this system of encryption and signing becomes a useful trust enabling mechanism without having to trust a third-party to "see" your messages before they reach the recipients.
Do you use any specific solutions that have fit your need? So far I've found that Signal fits my requirements most for encrypted group messaging and PGP encryption/signatures for email communication. You can reach me at firstname.lastname@example.org and encrypt your emails if you'd like. 😄