>About a month ago I heard Microsoft had their own Linux distribution to help Microsoft Windows users feel more at home. From memory, it was a rather simple GNOME setup. Nothing special.

You're confusing Microsoft's first-party Linux distro Azure Linux (nee CBL-Mariner) that is intended as a regular MS-supported OS for containers, VMs, servers, etc, with various Windows-like skins for Linux DEs that people have made for years.