If you’re okay with installing some third-party addons, Pidgin is capable of connecting to virtually every chat protocol today, including Matrix, Telegram, Facebook, and so many more.
I should really start to use pidgin again. Back in the day of MSN messenger was awesome, and bring me back a lot of memories. Are those third-party addons trusted and opensource?
Just about all of them are FOSS.
Some plugins are very outdated or no longer maintained (and maybe left there so others can look at the code and maybe fork or learn from it). Some (Mattermost) plugins are up to date and working fine. I think most if not all are open source.
I know for a fact that the plugins for modern chat networks are relatively up-to-date and working fine, with the exception of purple-matrix, which hasn’t been updated since 2016 and doesn’t support encrypted Matrix messages.
