On my chromebook I use crouton[1], which is arguably more "native". You get an Ubuntu install in a chroot and can even run X11 apps in a chrome window. I was even able to compile neovim, you just need to set it up to use the system's lua and luarocks.
They would likely restrict play store installs, and currently there is no way to side-load Android apps; the normal Android developer mode options does not allow side-loading anyway, much less an enterprise managed device. I don't think there's any way to "restrict" dev mode, necessarily... anyone can put any Chromebook into dev mode, and lose all data that was on it in the process.
[1] https://github.com/dnschneid/crouton