The thing about 20.04 I disliked is that they made the Ubuntu Software Center a Snap package, and removed the ability to add Flatpak support from it. I have an extension on 18.04 that lets me get all 3 package types from Ubuntu Software.
Also Gnome Software Center(which is included in Pop-OS) has the option to download from all 3 sources.

Elementary's App-Center has hundreds of apps from developers that are made just for Elementary, and they also have Flatpaks available.