When I had reported to Luke Short – the main developer behind WinesapOS – that his distro wouldn’t boot on a MicroSD card on the Steam Deck, he personally saw to it that he would replicate the issue and fix it. As such, we now have a new update to enjoy: 3.1.1. I can now confirm WinesapOS runs on the Steam Deck when it’s installed on a MicroSD card. Display is rotated (though I’ve found this to be a very common issue with distros outside of SteamOS).