@Billie On phone, I use Element.
On desktop, I use element in Ferdi (basically the web version) but I have heard some good things about Nheko Reborn and Fluffy.
My dad (a non-techie) uses Syphon on his phone.
A friend of mine uses Gomuks (a terminal client)
That's the magic of the Matrix protocol.
There are plenty of options around.
Fosstodon is an English speaking Mastodon instance that is open to anyone who is interested in technology; particularly free & open source software.