The Elder Scrolls IV: Oblivion's Steam listing states it can run on the Steam Deck. The Unreal Engine 5 powered game has some steep requirements and takes up 120 GB of storage. https://www.notebookcheck.net/The-Elder-Scrolls-IV-Oblivion-is-Steam-Deck-Verified-despite-its-seemingly-high-hardware-requirements.1003248.0.html
"should get you to a playable 30 FPS"
I'll leave how 'playable' 30 FPS actually is to others.