Find a program to work on and fix issues that interest you. Start small. It is satisfying to fulfill peoples feature requests, even if the feature isn't helpful to you. You know that you made this person happy and there are probably more people who wanted that feature too
If you want to get emerged into the linux world and get broad understanding then I recommend watching videos on youtube by DistroTube. Adjacent, kinda more advanced channels are Luke Smith and Brodie Robertson.
If you just want to use linux and be done with that topic, you can use linux mint. What you have to know is that you get all software from the software center, not from websites. The rest should be very familiar.
Your client encrypts and decrypts everything, so it is actually not a privacy concern regarding message content when we don't know what the server does.
F-Droid doesn't want to host Molly because Signal doesn't want any forks on F-Droid. Seriously, that's the whole reason. Molly devs would be fine with it.
Molly is actually reproducible and has a fully FOSS version, so it is trustworthy.
that doesn't keep packages installed between distro reinstalls or swapping between entirely different distros. I'm talking about the actual packages and app data themselves that are contained in home.
It's auto installed because everything is portable
Then you didn't explain it very well. Your former comment clearly states that copying the files keeps the packages (so you don't have to redownload?) and the data, but "doesn't keep packages installed" (hinting that .desktop files don't get found)
I'm pretty sure modern programs by modern people are primarily released as Flatpak while every other traditional package manager comes second, if at all.
If you want to measure popularity, you can see the download count of programs on flathub.org .
550,000 installs of LibreWolf is not niche.
Install everything as a flatpak, it is the future. Anything else will be outdated or can lead to headache (dependency issues).
Here's a simple GUI video downloader.
Here are elegant, easy to use apps that cover many different needs.
EDIT: Tell me where I'm wrong