My understanding is that HDR formats utilise 10-bit color formats rather than being strictly equivalent.
From Wikipedia:
HDR video refers to a video encoded in an HDR format. Thoses HDR video have a greater bit depth, luminance and color volume than standard dynamic range (SDR) video which uses a conventional gamma curve.
As it alludes, HDR is more than just a 10-bit color space. Encoding anime in 10-bit doesn’t take advantage of the greater luminance or dynamic range. It does take advantage of the color space to minimise banding.