Like others, I also use keybase.io. By design it is not connected to the phone number, I can prove by myself the identity of the recipient and yes, it has exploding messages. They had a fiasco with unwanted cryptocurrency but now it is mostly forgotten/forgiven.
If you live in a condo, what about sharing your internet on the guest WIFI network? Does it make sense? Will people misuse it? (It probably violates TOS, I guess.)
I remember when I tried to do the same thing three years ago (the year before I deleted my account) – Unfollow every person. AFAIK I had 600+ contacts.
What was funny, after ~300 clicks I got the captcha to fill and 14 clicks later week block with a message: "This is not a proper using of the function". Also, FB was hypocritical. It allowed me to click to follow again, just unfollow was blocked. :-)
https://ibb.co/M25sXX1
https://ibb.co/RcM62TD