I'd like to second Snikket - it's designed for this use case and is very simple to set up.
If you'd rather not use Snikket, check out these recommendations for clients and servers.
Hope it works for you! Feel free to reach out if you have any questions.
Different strokes for different folks! I've been fortunate enough that many of my family and friends have been happy enough to follow me.
But I don't disagree with you, Signal has a much more recognisable brand and better user experience. These are things that we need to improve if we're going to get anywhere near the level of adoption Signal has.
How I Got a Truly Anonymous XMPP Account:
Sorry, it's a cheap joke, but it still baffles me that Signal requires a phone number, so I felt I had to post it :)
Of course, this is not XMPP-specific either, just my protocol of choice, there are many other open alternatives that also offer such functionality.
I originally suggested Monal to my friend (who is quite into iOS and really appreciates a well designed application) and she found the same, but then she tried Siskin, and was happy enough to use it to this day.
Just for reference, here are my favourites on each platform.
Each support modern XMPP extensions, interoperate very nicely with each other, and (at least in my opinion) look good!
As a note of caution, I used Oracle's free tier to run a personal Matrix server, and it got deleted without any advance warning after a few months. I migrated to another provider and haven't had any issues for 2+ years now.
I've had good fortune converting some family and friends to use XMPP.
People always mention fragmentation, and while there is some truth to it, it can be massively minimised by choosing blessed clients and servers for them to use.
In my case, I run my own server, and thoroughly test the clients (especially the onboarding flow) that I expect them to use, so that any question they have, I can help them out with quickly. Since we're all on identically configured servers, it minimises one whole class of incompatibilities.
There is still unfortunately a bit of a usability gap compared to Signal - particularly on the iOS clients. But they have come a long way and are consistently improving.
Perfect, now you just have to wrap your program inside a debugger in production!