A while ago I was looking for a list of available Flatpak repositories but didnt find one, so I made my own.
Note that most developers put everything stable onto Flathub. But there are a ton of other remotes I found, most are for development, beta and nightly things, but there is also a Firefox ESR remote and more interesting stuff to find.
I want this list to be complete so if you know any more please open a PR or Issue!
(I used this list to include a few more tutorials like Flathub subsections)
I’d call it ppa without the drawbacks, aka. breaking the OS on upgrade (from wrongly packaged or out of date ppas).