You're right on the money. They're trying to region lock it. Unlikely that US and possibly UK customers will get it.
We also found references to a region lock in this API, which suggests that Apple could restrict it to specific countries. This wouldn’t make sense for MDM solutions, but it does make sense for enabling sideloading in particular countries only when required by authorities – such as in the European Union.
Some old video codecs were proprietary and had to be installed afterwards from a separate repository or package, that might be where that notion is coming from. That being said once the relevant codecs are installed (open-source or proprietary) things just work fine, or you could install VLC or mpv and just call it a day.