I found MoonDeck while perusing the Decky plugin store and it’s absolutely awesome. I’ve had Moonlight and Sunshine set up for a while because Steam streaming is very inconsistent between Deck and Linux, but I didn’t use it often because it’s a pain setting up launchers in Sunshine for each individual game. MoonDeck takes the hassle out of that completely, and I find myself streaming GPU-intensive games to my living room much more often nowadays.
I highly recommend it!
So that file can go anywhere you want, but
~/binis a good spot (or~/.binif you like a tidy home folder). You can name it whatever you want, but I’d personally name itsteam.sh. And then in the Buddy settings, use that file as your new Steam binary.