Valve’s Steam Deck is basically a handheld gaming PC, so naturally there are going to be users who want to install the newest version of Windows onto it. However, Microsoft’s push for security in Windows 11 means a lot of systems either aren’t compatible or will need a firmware/BIOS update in order to run it. This throws Steam Deck’s ability to run Microsoft’s upcoming operating system into doubt, but Valve has assured PC Gamer that it’s making Windows support a high priority.
The reason so many issues are cropping up surrounding Windows 11 compatibility is because Microsoft will be requiring Trusted Program Module (TPM) 2.0 support. While most newer machines have the means to support TPM, they don't have the function enabled by default. So, in order to run Windows 11 properly, many users will have to either download a new BIOS for their system, manually enable support, or install a new motherboard.