I'm quarantined upstairs while my family lives downstairs and only have a surface pro up here.

Is it possible to game with a surface pro with like a controller or anything?

No clue, but I'd ask the Nerdery

Surface Pros run a full version of Windows 10, so if it's beefy enough to handle games, you should be able to bluetooth connect a controller to it and play some games from Steam.

Don't expect the same performance as a gaming rig, though.

You can but you're not going to get the same performance as if you were on a console or gaming computer. There are some games on Steam that will be good for playing on a Surface Pro. If I remember correctly, Steam has a forum/group for Surface Pro gamers and it will have recommended games.

If you want something more MMO, you can always download Old School RuneScape. Yeah it's an old game, but it's a good time killer.

I just went ahead and bought a TV and an Xbox series x or whatever

Cannot be stuck on the 2nd floor of my house without entertainment for 2 weeks

You can connect your surface pro remotely to an Xbox and play it anywhere in the house. Just use the Xbox controller set up on the surface pro.