It is part of the High 4:4:4 Predictive profile, but you can use it with 4:2:0 subsampling if you want. It's more accurate that the all profiles H.264 defined kinda sucked except for Main, and no one really thought 10bit, 422 or especially 444 were useful and completely ignored those profiles until it was too late to be worth implementing.
Actually, lossless video is also rather marginally useful, especially given the decode cost of the arithmetic coding H.264/HEVC/VP9/AV1 have.
Ironically for your example, lossless, 4:4:4, and 10bit H.264 actually will play back on the new M1 Macs in QuickTime Player, though with a warning about it.