"Note that a game doesn't necessarily have to be in the Xbox Play Anywhere program in order for a purchase to be valid for both Windows 10 and Xbox X/S/One, as long as the Microsoft Store page's "Available on" section says they're available on both platforms. A makeshift list for those games can be found at this search page."
Should those games appear in this list, as well? The only difference is that they are not "advertised" as Xbox Play Anywhere titles even though their functionalities are the same, AFAIK. If not, perhaps a different list should be created...?