alt Hacker NewsThat... Shouldn’t be terribly difficult? Though I don’t believe UEFI has sound drivers (you’ll have problems writing one yourself because even frickin’ sound-codec chips have NDA-only datasheets these days), and the stupidest thing is that the “graphics output protocol” doesn’t indicate vsync so you can’t do tear-free blitting, which is literally worse than VGA.
Most support Intel HDA.
The problem is that people don't use onboard audio anymore (because its incredibly and audibly noisy). They use USB or Bluetooth.
Bluetooth absolutely isn't standardized and is a mess, and USB miiiiiiight be okay if you limit to a subset of EHCI and USB Audio Class 1.0 devices.
At this point, its easier to just use Linux and run your game as pid 1.