Actually yes, this is exactly the case. And they've done it in a really shady way if you ask me (or Clem, the main guy over at Linux Mint).
I've been using Fedora on a little tablet I've got, and it uses either .rpm packages or flatpaks. The GUI package manager lets you select which repository it pulls from (either .rpm, or Flapaks can come from Flathub or their own repo, and clearly displays this). If invoked from the terminal, the DNF package manager gets you .rpms, and Flatpak gets you, well, flatpaks.
Ubuntu uses the APT package manager with .deb packages, and Snap with snap packages. But sometimes if you do an apt-get install, it installs a snap instead. That's some Microsoft level bullshit.