With tweaking, I’m sure most games would be just fine running on the Steam Deck. It’s just a matter of figuring out the right settings.
I find older Windows games have the most issues like Oblivion or Morrowind if you install the stock standard GOTY. However, there’s an open version of Morrowind that can be run via Lutris its just a bitch to get Lutris to work. Persistence is key.