For the moment, yes! I just ran the installer with Lutris + wineGE 8-26 and it has been working fine for the few hours I played. No telling if it will change though.
From my very non-scientific tests on an AMD 6800U device, running steam via Bazzite + distrobox gave me a 0-2fps boost versus running steam on uBlue Kinoite with Flatpak. Mangohud was slightly easier to manage with Bazzite's distrobox setup. I did not test power consumption between the two for mobile gaming.
The listed countries look like countries that often get regional pricing. Was the geo blocking to allow for regional pricing in those areas?
Single player or multiplayer coop up to 3 people. It's not a mmo or anything of that nature, no. Multiplayer progression works like in Grim Dawn where the host progresses their game and character; people that join don't progress their own campaign progress, but do progress their character.
Edit: more info.