Not sure how the XDR is coupled to this. That external box takes SDI input and produces HDMI output. The XDR doesn't fit anywhere in that mix ( Thunderbolt input primarily. Underlying takes an two DisplayPort display streams. A different basic data encoding format than either of those other two. )
As I linked in post #2 above , there is suppose to be underlying hardware to adjust the calibration. It is missing software, firmware, and driver to be enabled. I suspect there is different low level API that 3rd parties will have to deal with that will be substantively different than other monitors. [ would also be a small sum that it will use the new kernel driver API that Apple is rolling out with 10.15 and later macOS versions. Which is another hurdle to get over that can impact timeliness . ]
Ready to rumble with another HDMI input monitor. If the primary delivery platform is a device with HDMI that would be a good sanity check for the "final delivery point" reference check. But the XDR wouldn't be playing the final reference check role.