Follow these simple steps to start using Flatpak
To install Flatpak, run the following:
$ sudo apt install flatpak
Flathub is the best place to get Flatpak apps. To enable it, run:
$ flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
To install light and dark themes, run:
$ flatpak install flathub org.gtk.Gtk3theme.deepin $ flatpak install flathub org.gtk.Gtk3theme.deepin-dark
To complete setup, restart your system. Now all you have to do is install some apps!