"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."
It's a Steam Deck. Connected to Steam. I don't think many people are suffering from a shortage of Steam games to play.
"Yes, Andrew Fear (great name by the way), when I finish playing the 500 games already in my library, and start playing the 200 I already own but haven't started yet... which all work on it... I mean, yeah, I'll definitely look at whatever it is you're on about"
[Edit] I have misunderstood it as a game rental/streaming service, rather than a computer rental/streaming service