It really depends on what the site’s terms of service/usage agreement says about the content posted on the site.
For example a site like Art Station has users agree to a usage license that lets them host and transmit the images in their portfolios. However there is no language saying the visitors are also granted these rights. So you may be able to collect the site text for fair use, but the art itself requires reaching out for anything other than personal/educational use.
The short version is that there are two images and sidecar/xmp file sandwiched into one file. First is the standard dynamic range image, what you’d expect to see from a jpeg. Second is the gain map, an image whose contents include details outside of SDR. The sidecar/xmp file has instructions on how to blend the two images together to create a consistent HDR image across displays.
So its HDR-ish enough for the average person. I like this solution, especially after seeing the hellscape that is DSLR raw format support.