If you’re talking browsers it’s poor. But HDR on displays is very much figured out and none of the randomness that you get with SDR with user varied gamma, colorspace, and brightness. (That doesn’t stop manufacturers still borking things with Vivid Mode though).

You can pack HDR in JPG/PNG/WebP or anything that supports a ICC and Chrome will display it. The actual formats that support HDR directly are PNG (with cICP) and AVIF and JpegXL.

Your best bet is use avifenc and translate your HDR file. But note that servers may take your image and break it when rescaling.

Best single source for this info is probably: https://gregbenzphotography.com/hdr/

Say gigantic. Now what you’re going to do next is stop with your ANTICs and enunciate the gig the same way.