If it's like the steam deck version, it'll be based on Arch with a bunch of steam-specific patches/configs to make games run more easily (with the added bonus of making non-steam games run pretty well too). Steam exists to sell games, and if they want to make it easier for me to play games, that's fine by me.
Not sure what a Microsoft distro would look like, but if they make a distro that'll run Xbox games with gamepass, I'd give it a shot.
Another nice bonus for either/both of those situations is that it wouldn't be too hard to incorporate those changes into other distros. That way people who want more of an "install and go" experience would have their official distros, people who like to tinker could work on importing the official code into their unofficial setup, and people who use arch btw can install it from the AUR.
Y'all are guns cuz of your stupid