XMPP was the messaging protocol used defacto back in the 2010s. It's a federated platform much like Lemmy but the base protocol itself is very simple so it relies on protocol extensions developed by the community. Not all clients sport the same features and not all hosts allow the same things.

An easy start into XMPP is to use the Conversations client in Android which lets you sign up gratis to conversations xmpp domain. It is available free of charge on F-Droid but you can support the devs using the Google Play version. On GNU/Linux there aren't too many XMPP clients but the best ones are Gajim, Dino, and Converse.js

Element is the matrix client built by the Matrix devs. Matrix dot org has some special features like using Jitsi for video conferencing calls etc.

[–] Red_sun_in_the_sky@hexbear.net 2 points 4 months ago

I have seen the fdroid app yeah. I guess I will try these and see.