Where do you get the emulators from and how do you get the roms on there?
On Xbox there's an app called "Activate Dev Mode". Download that and it will give you a device activation code and a link to enter on PC. I wasn't signed up for their individual dev license, so I purchased it for $19.00usd. The item is called "
Windows and Windows Phone Annual Developer Registration" in order history.
Once you do that you're able to enter your Xbox device code from the Activate Dev Mode app. It will say it's updating and once it's done to return. I returned, even after a restart, and the update didn't progress the screen. That's where the fix from SquareBanana comes in...
I was having the same issue. However I've managed to activate dev mode through the hidden developer settings menu rather than the dev mode activation app. To access the hidden menu go to Settings > System > Console Info > Press LB RB LT RT > Developer Settings > Developer Mode
After you tick the dev mode box the console will restart in developer mode. WiFi wasn't working for me, so I used ethernet. In the bottom right corner it will have an option for Remote Access info/settings. When you navigate there it will have an IP for the Xbox Series S. I typed that in my browser on PC and it opened the web console for managing development. I hit the "Add" button up top and selected the .appxbundle RetroArch file. It takes a bit to transfer and then it will just pop up in your list on Series S and you can run it.
I haven't tried N64, but PSX, SNES, and Gen work pretty effortlessly. PPSSPP works with Tekken 6, but not FF: Crisis Core. I can't get GCN or DC to work right now, it might have to do with loading from USB I get an error something like "Content load error" which when I googled might be related to USB or somebody suggested changing the allotted Dev Mode space.
This is super early in the game, of course, so it will get much easier in the future. I remember going through all the growing pains with PS Classic only to find a pre-made 128GB zip you could download to a flash stick that was pre-loaded with everything perfectly like it was done by a team or autist. Good luck!