As someone who uses Flatpak you can still use the terminal to install, uninstall and do maintenance, not sure why people believe terminal is useless with Flatpak 😞

Flatpaks are containers, same as Snaps, I personally prefer Flatpaks over Snaps, but just my personal choice. I use Flatsweep and Flatseal apps to help administrate Flatpak apps, but use terminal as well 🙂