Again, that is fine. Besides getting an uncompressed 2 channel signal; anything above 2 channels is going to be compressed and frequencies carved out of the additional channels due to the encoding process. Thus a loss of fidelity. You "may" get a multi channel signal, but it is not 1:1. There are plenty of papers written about the subject since it's nearly a 50 year old technology.
My laptop definitely supports up to 8 channels (7.1) of uncompressed PCM over HDMI. I've tested my receiver up to 5.1 (I don't have an 8-speaker setup) and it works.
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I have an Intel IGP; Intel has supported this since the G45 (Core 2 Duo era), AMD added it in the HD 4800 era, and nVidia in the GeForce 8300 era. Support for this is over a decade old at this point.
The "stereo only uncompressed" is a S/PDIF legacy, and while HDMI does support S/PDIF, it was already "the bad old way" when Bluray players came out (though it took a few years for discrete GPU makers to catch up).
DTS and Dolby are unrelated to uncompressed LPCM. HDMI 1.0 supports up to 8-channels, up to 192kHz, and up to 24-bits of depth. In practice, my laptop to my receiver can definitely do 24-bit 48kHz PCM at 8 channels, and that's certainly "full fidelity" for most setups.
Uncompressed multichannel LPCM works along-side video just fine. The only thing you have said in this thread that is true has been about eARC/ARC, yet you've doubled-down on your statements even when I made it clear that I'm not using ARC.
