Hey! If you haven't got someone already I'd be keen to help out with music/SFX. Here are some examples:
Music: https://youtube.com/playlist?list=PLhdqZ1WvzEgCujtDjO1gl_Bhh6gfMpU4U
Sound Design: https://youtube.com/playlist?list=PLhdqZ1WvzEgBrORQUF2TtE5QEx3BTAzRy
Just so you know, I don't have PICO-8 so I might not be able to help if you take that route. In any case, let me know if you'd like to collaborate!