I have a 1st gen Steam Deck (256gb), and it has supported wake from bluetooth peripherals for a while. I've only tested it with a PS5 controller, but it works. [EDIT: btw I use the official dock. Idk if it'll work with others]
I use my SteamDeck as a streaming device too, and since my TV is connected via HDMI, waking the console also wakes the TV. So I can start playing/watching anything by just turning on my PS5 controller (which is not ideal because the PS5 controller has terrible battery life and is often dead when I need it, but that's a different issue)