The GBA version is also playable on SteamDeck.

You need getting the RetroArch from the Steam Store.
https://store.steampowered.com/app/1118310/RetroArch
Also needed the mGBA core.
https://store.steampowered.com/app/1227448/RetroArch__mGBA/
However, you must first copy the ROM files under /home/deck as follows:
We have written this article to help you if you want to play only with SteamDeck, although we do not think you will have any doubts if you are using a PC.