I reached out to Microsoft through their support channels.
At present, there is no way to view a list of all of the games you currently own. Instead, you can look at available games on a specific console, and games you have deliberately purchased.
View All Games That You Have Explicitly Purchased
You can view all of your Microsoft Store purchases through your order history, found here. Make sure that you have "Digital" and "All available" selected from the left hand menu.
This will show you all digital purchases on record. I can personally go back as far as May of 2011; for me, at least, this represents my entire digital purchase history.
It will not show you games that you own through the Games for Gold program, as these transactions did not count as actual purchases.
View All Games for a Specific Console
You can view all games available on a specific console by navigating to the "Games & Apps" tab on the specific console. You should be able to look at all available games, as well as all of the games made available through the Games for Gold program.
As mentioned, this will show many games from other consoles, specifically when looking at the majority of the Xbox 360 titles that are compatible and can be installed to Xbox One and Xbox Series XS consoles. You may be missing the few titles that are not backwards compatible, in which case they will only show up on Xbox 360 consoles.
I do not personally own an Xbox Series XS console, so I am not able to test the theory, but you might also see your Xbox Series XS titles when viewing from the Xbox One; I can confirm that you can for Game Pass games, as I can view "Medium" despite the game only being available for Xbox Series XS.