If you want to use WOL you’ll need an adapter/dock with an Ethernet port.

Then use nmcli (network manager cli) to accept magic wake-up packets: nmcli c modify “Wired connection 1” 802-3-ethernet.wake-on-lan magic

See more info here: wiki.archlinux.org/title/Wake-on-LAN

Then you just send a magic packet to your Steam Decks IP whenever you want it to wake up.

Note: if you own an OLED Steam Deck technically you can just do this over Bluetooth with a controller instead, because of the hardware update.