Flatpak (flathub) is a universal app store. You can install pretty much any app from it, but you do need to be careful of what you install, as always.

Usually software centers have it enabled (supported) by default, so that you can install app from flatpak within the center.

There are other options of install source, like the distro’s own installer - you can think of them as another “app store”, one which is more restricted and more secure.

I am inside neovim and I cannot quit

Headlines, lol

How did you manage to develop the application? Would have taken tons of time.