OVERVIEW
"There’s a reason people often say, 'The picture doesn’t do it justice — you had to be there.' Until recently, our monitors simply couldn’t display what we saw with our eyes. That’s all changing now thanks to HDR (high dynamic range) display technology.
This isn’t just a small improvement—it’s the most significant leap in image quality in decades."
HDR (High Dynamic Range) is the next advancement in photo and video viewing. In my opinion it is a much bigger advancement than 4K or other image viewing improvements.
Unlike traditional "HDR" photography which is just designed to simulate HDR on a regular display true HDR can only be achieved with the right hardware and software. Essentially true HDR is the ability for a display to show extremely bright areas and extremely dark areas at the same time much closer to what our eyes can see. You have to see it in person to grasp it. It's more than just added saturation or brightness, it's a whole different way of displaying an image that much closer matches reality and the way our eyes work.
See here for ways to check if your device supports HDR viewing.
Requirements
Proper support for HDR is still limited. Both the hardware and software used for viewing HDR needs to support specific formats like HDR10+ or DolbyVision.
Hardware support for HDR can currently be found on the following devices ( + means "or newer" )
                                •📱iPhone 12 + / iPad Pro (disable Low Power Mode)
                                •📱Google Pixel 7 +
                                •📱Some Android devices (varies)
                                • 💻 MacBook Pro 2018 +
                                • 💻 MacBook Air 2018 +
                                • 🖥️ MacMini 2018 + (with compatible display)
                                • 🖥️ Various TVs and computer displays
Software support for HDR is very limited. Sites such as Instagram and Threads have some basic support but most other sites currently do not. Instagram will display HDR content in the smart phone app (if you have a supported device) and in a desktop web browser, but only if the browser supports HDR viewing such as Google Chrome (Safari on macOS does not work, even if you have an HDR display).
When viewing an HDR photo on a supported device it can take a few seconds for it to switch to HDR mode. Be patient and make sure the required HDR settings are enabled for your device. 
HDR Content
Below I have put together a sample gallery that can be viewed in a support app on a supported device / display / browser as per above. I will start including selective HDR photos on Instagram and other platforms as they start supporting it.
(View the gallery using a compatible display like on a 2018 or newer MacBook Pro and using Google Chrome, both of which are required to view HDR properly)