“There is not a native app on Steam deck today,” said Andrew Fear, GFN boss, back in January. “Use a Chromium browser to make it work. I would say that both Nvidia and Valve, I think we’re both interested in making [GeForce Now on Steam Deck] better. But we don’t have any announcements on a native app coming to Steam.”
That’s correct. I used to do most of my steam deck gaming by streaming games from my desktop. It’s a seamless experience, as much as anything is on the Deck. I still prefer to stream games from the desktop that benefit from better hardware, like BG3.