That's the most enjoyable part of the game design and yet I haven't been able to spend too much time on it yet! Similar to character designs in other games, it has to wait a bit until the core is finished. I do have a bunch in mind, and the goal is of course to make them as varied as possible.
what ideas you already have? (if you are ok to say them ofc) and you could do somthing like a suggestion chanel in your discord server (if you didn't already)