99.99% of all games are 8 bit.
the difference between professional GPU and normal GPU is the support for openGL windowed 10 bit in 8 bit RGBA by misusing the A channel at least for this topic.
as far as i’m aware VLC is unable to output 10 bit. 10 bit input is a basic feature.
madVR and MPDN can output 10 bit but they need a fullscreen surface to do that that’s just how directx works.
nothing has change on the side of bitdeep input to a GPU driver on nvidia or AMD both can do even 16 bit for many many years now.
windows 10 photo is clearly 8 bit output without dithering it supports 16 bit images as input but the output is 8.
mpv got an update for 10 bit on windows i never tested it mostlikely has the same limitations at directx.
are you running constantly in HDR mode or something and how are you proofing something is rendered in 10 bit?