If you were lucky enough to get your Steam Deck already the promised Windows drivers have now arrived. For right now Windows 10 is supported, although Valve is promising Windows 11 support once they incorporate fTPM into the device UEFI. Also dual-boot is not currently supported, but it is something Valve is working on and promising to deliver in SteamOS 3. With the addition of Windows drivers Valve has also added instructions on how t o do a system recovery and get SteamOS back in the device.
As for the driver release you have drivers for GPU, WiFi, and Bluetooth, but audio drivers are missing as of right now. If you want to use Windows on the device Valve suggests using Bluetooth for audio or the USB-C connection until they finish the drivers. This means that you’ll get no audio from the speakers or 3.5 mm audio jack using Windows currently. No Windows support is being offered from Valve so it is up to you to get it installed and working on the Steam Deck.