I have been working with HDR for quite awhile. Of course you need HDR TV. I have many videos (here are the Spain travel HDR videos https://www.lifestorypictures.com/spain-travel/) mastered in FCPX/Compressor w H.265 and hosted on Vimeo, which, you are right, can only be viewed with combination of Apple TV box and HDR TV. YouTube, on the other hand, requires a combination of Google Chromecast Ultra and HDR TV. However because of the, how should I say, competitiveness of Apple and Google, Google does not allow HDR metadata from FCPX to “trigger” HDR content on YouTube. They recommend a kluge software called “Matroska Colour Metadata Ingestion Utility” to “dress” video with an “appropriate” metadata. I tried to use it – it does not work on Mac. I did not try to try it yet on Windows.