All good
10 bit SDR is totally valid, especially in the premium case where source content is at least 10 bit 4:2:2. It's unfortunate that the first wave of hardware HEVC decoders were 8 bit, else all HEVC would be 10 bit today.
We only encode 10 bit HEVC on the service I work on (SDR, HDR10, and Dolby Vision)