And? For anyone who actually wants another app store, that’s not exactly a high bar of technical know-how. In fact, for the most part it’s the way stuff works on other platforms as well (provided you even have the option of choosing on those).

If you want to install Steam on Windows you need to download it, click through, and run the installer.

Linux may have snap etc, but to add unofficial software channels you need to manually edit things.

Apple straight out says “nope” on iOS unless you jailbreak.