If you don't want to install extra software, you can manually swap appearance data between a "template" character and your main character. This is the most stable method but requires several steps.

Starbound mods work identically on Steam Deck because the game runs through Proton. However, the directory path differs:

For a long time, has been the go-to external save editor. It allows you to open your save file and directly change your hairstyle, colors, and even your species.