Another idea...

If I were to make a #Linux distro...

For as many common package managers as possible that aren't in my distro, I'd make the commands for them bring up a bit of text explaining which package manager IS installed, and the commands for it.

I've used Linux a while, and even I get a little lost trying a distro I've never messed with before if it's using a package manager I'm not familiar with. Zypper on OenSuse had me stuck for a bit.