Lightroom recently got proper support for HDR processing. UI-wise there are some good ideas worth stealing:
As I mentioned further up:
I do wonder what Google’s play is exactly. If this is intended to be the JPEG Gain Map implementation done in cooperation with Adobe, or if they just seized the opportunity before anyone else. While there are a number of articles about UltraHDR out there, they are typically not much more than fancy PR pieces, so hard to know for certain. And I have even seen it described as proprietary, which it is clearly not.
Google’s reference library indeed works by ingesting both an SDR and HDR version of the image, deriving the gain map from the difference.