The Steam Deck is not discontinued. It's actually quite new, with the first shipments going out to normal customers at the beginning of this year, and more and more going out now. I got mine in June. Valve made a reservation process that required an old enough Steam account and $5 refundable reservation to avoid scalpers.

Regarding the ecosystem, the Steam Deck is a x86 PC. It comes with SteamOS, which is an open Arch Linux based distribution. You are free to install other operating systems like Windows on it. The out of the box Steam experience is quite good, with lots of games on the Verified list[0], and they play really well. People also install non-Steam games and software, including console emulators, and there are growing communities around that.

[0]https://www.steamdeck.com/en/verified

Found the time traveler.

Steam deck can be a bit of work doing things like getting epic games to run, file transfers, and setting up the controls for games that aren't fully supported. Many games work flawlessly like they're on switch, though. It depends on whether occasional issues that force you to tinker are fun or not.

Elden Ring plays well. I don't plan on using my switch OLED until the next Zelda comes out.