Sure, early Old games. The developers behind Dolphin have just shown the Gamecube and Wii emulator running on the Steam Deck.
The tweet from the Dolphin Twitter is simply an image of the Gamecube classic F-Zero GX running on Steam Deck. There's no other context for the image, but it's the first tweet outside of the usual status report updates that the has provided in months – so clearly, the developers think it's a big deal.
Emulator devs were looking at the prospects of getting their software running on Steam Deck as early as the platform's original announcement. "Everyone I know has relatively high hopes for the Steam Deck right now," Dolphin developer JMC4789 told PC Gamer last year. Judging by this single image, those hopes were well-founded.
A handful of emulators are available on Steam directly, primarily through RetroArch, though Dolphin is not one of them. Steam Deck promises to be friendly to installations outside the Steam interface, however.
— Dolphin Emulator (@[email protected]) (@Dolphin_Emu) February 18, 2022
The Steam Deck release date is set for February 25 – assuming you got an early reservation in, that is.