It’s easy when you didn’t know something that is completely reasonable not to know, like in this example, but it’s always good to admit your ignorance.

Yes, you can use their exact build environment straight from GitHub. You can also use Molly.im which is another app that i think is a fork? Im still investigating it.

That’s kind of a core tenet of libre/open software, innit? Independently verifiable software that you can change at your pleasure.

I was looking at Molly.im and it has its own f-droid repo. There are two options: with and without Google servicios.