Yeah, you just need to make sure that you support 256+ color terminals and then create some way to define a theme in a single file and have some theme picker in the TUI (or at least in config file). It's ok if it's ansi codes, etc.

If you want to go fancy you could also support CSS style colors (#abc, #aabbcc, rgb(0,0,255)), that would increase the number of people willing to create a theme for you 😃

I can do a quick theme for you if I have time and if you have easy way to create the theme 😉