TIL that M4 Macs (but not M5?) support HDMI CEC, could be cool for a home theater PC (I don't think any PCs support this?) https://support.apple.com/en-ca/108928
Connect to HDMI from your Mac - Apple Support (CA)

Mac computers can use an HDMI cable or adapter to connect to a TV, display, or other HDMI device.

Apple Support
@christianselig it will work on the steam machine.