Valve has shared most of the drivers necessary to run Windows 10 on a Steam Deck. Additionally, the company has confirmed that Windows 11 and dual-boot support are also in the pipeline, but neither officially work at present.
https://www.notebookcheck.net/Steam-Deck-receives-Windows-10-capabilities-with-official-drivers-as-Valve-confirms-Windows-11-and-Dual-Boot-support.607764.0.html