SimpleX - the first messaging platform operating without user identifiers of any kind - 100% private by design! iOS and Android apps are released 📱!
https://simplex.chat/ - scroll down to the bottom of the page; "Terminal CLI" - has been there since the beginning of the project and actually was what you needed to use before the mobile apps were available.
Sydent: Reference Matrix Identity Server
If you really want to be decentralized, I would say https://matrix.org/
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A private messenger for Android.
Is there any reason why https://getsession.org/ is not in your list?
Simple Self-hosted messaging and videocalls whatssapp/telegram like
2 projects | reddit.com/r/selfhosted | 23 Dec 2022
SimpleX Chat – the first messaging platform without any user profile identifiers (not even random numbers) – v4.3 with instant voice messages and irreversible deletion of sent messages is released.
3 projects | reddit.com/r/PrivacyGuides | 6 Dec 2022
Secure, Private AND anonymous IM (compatible with linux)
2 projects | reddit.com/r/privacy | 1 Dec 2022
SimpleX chat v4.5-beta is released - with user chat profiles and message drafts!
1 project | reddit.com/r/SimpleXChat | 30 Jan 2023
SimpleX Chat [lack of] Android 32 bit CPU support, up to $20 to upgrade
1 project | reddit.com/r/SimpleXChat | 16 Jan 2023