I have a steam deck oled and love it, but the SOC is slightly old now and was never the fastest. If you're playing slightly older games or are fine with slightly lower settings, than it's still great.

SteamOS is great, but I think you can install it on other handhelds as well. It sounds like current competition isn't great unless you're willing to pay a bit more and the steam deck 2 isn't rumored to come out soon, so the steam deck is probably still worth purchasing tho.