Sign-up still requires a phone number… -.-"

Thanks for the warning – that was my first question. It is my top reason (among many other reasons) for avoiding Signal.

Checkout Matrix/Element or Session,

All 3 of the sites you linked are Cloudflare sites (thus antithetical to privacy). Yes, I know you can use some of that tech without touching CF, but when they run CF websites it reveals hypocrisy & not understanding the goals of their audience.