Main 10 is the profile that matters
HEVC's base Main profile is 8-bit. HDR needs 10-bit, which means Main 10. An encoder set to Main will silently produce an 8-bit file, and an 8-bit file is not valid HDR10 no matter what colour tags it carries.
Where the metadata lives
This is the practically important part. HDR static metadata is not stored in the container alongside the video. It lives in SEI (supplemental enhancement information) messages inside the HEVC elementary stream itself: mastering display colour volume from SMPTE ST 2086, and content light level giving MaxCLL and MaxFALL.
The consequence is concrete. Any operation that re-encodes the video destroys this metadata unless it is deliberately regenerated. Any operation that copies the stream preserves it. If you need to change something about a finished HDR10 file, remux with a stream copy rather than transcoding, or you will lose exactly the HDR signalling you were trying to keep.
Support
Hardware HEVC decoding is near-universal on anything made in the last several years: phones, TVs, tablets, and every current desktop GPU. That is why it is the delivery codec for HDR rather than a more efficient newer alternative. See where HDR video actually plays.
Questions people ask
Will an HEVC file play everywhere?
On hardware from the last several years, effectively yes: phones, televisions, tablets and current GPUs all decode it in hardware. Older machines and some browsers are the gap. That near-universal support is why HDR10 delivery uses HEVC rather than a newer and more efficient codec.
Should I use AV1 instead?
For streaming platforms that support it, AV1 compresses better and handles HDR fine. For a file you hand someone directly, HEVC is the safer choice because hardware decoding is more widespread. This converter outputs HEVC for that reason.