Flatpaks are a convenient way to install software on Linux. Flatkpak is popular because its convenient to package applications once, work across a variety of Linux distributions, and is isolated from other applications.
Ubuntu and its related distros like Elementary, Mint, and Pop!_OS have access to an enormous software library. There are times when a particular program may not be available in an official repository or is lagging behind in updates. Ubuntu developed Personal Package Archives (PPA) as a way to easily create small personal repositories to deliver software that either doesn’t qualify for the official repos or that the developer may not wish to release there. While PPAs have waned in popularity as Flatpak and Snap have received more attention, there are still many great PPAs available.
These Linux distros are simple to install, ready to work, and easy to use.