On how to fork a GNOME Core app without meaning to do so – GNOME adventures in mobile

I know very little about contributing to open source but appreciated reading this. Seems like often the interpersonal element is the biggest challenge and the author handled it well.

Was this app removed from flathub¿? I wanted to try this after reading about it but can't find it on flathub. The flathub link given on the project gitlab page also leads to 404 page not found error