It's worth noting the reason why Molly isn't available on F-Droid proper: it's entirely F-Droid's decision. F-Droid policy requires that developers support (or do not oppose) inclusion in F-Droid, which Signal's developers haven't. Signal's developers are also hostile towards forks and do not want them interoperating with Signal. Thus, F-Droid does not allow Signal or any fork of Signal.

https://gitlab.com/fdroid/rfp/-/issues/2297

I am not really a fan of this decision, I don't think it's logical that an upstream can forbid a fork from being published anywhere - but that's F-Droid's call to make.