It’s probably a pain to set up in Windows. In Linux, it just works, there’s nothing to set up. I’m using it right now.
OP really should have mentioned their OS.
Edit: Actually, nevermind both my posts. I know DRI_PRIME works by using my APU for regular desktop activity, and routing discrete GPU output in whenever a game is being played. But I don’t know if it’s possible to make it use the dGPU all the time.
Even if it did, it would only work inside the OS, so if you had to boot into the BIOS for anything, you wouldn’t have a display. So for all intents and purposes, it wouldn’t really work.