https://www.olsenhome.com/gif/compuserve-big.jpg
Since it was announced in 1987, if they mentioned the pronunciation it was soft G. The inventor and CompuServe would tell you it was soft G. CompuServe’s applications would tell you if soft G in their docs.
It’s even in the documentation of PNG which came out 7 years later that says soft G is correct in GIF, and they wanted people to pronounce PNG as “ping”, not “pinj”. (Yes, really)
See https://www.olsenhome.com/gif/ for more examples.


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/