What functionality do themeforest customers need?

Hi, everybody. I’ve never tried selling themes on Themeforest and I want my first try to be very successful. My theme has a wonderful and not banal design, 23 self-written shortcodes, a good framework, a visual editor (modest), but I still have one huge problem: functionality. As far as I understand, all the functionality we are is wordpress api customizer? Tell me what features should be added to customizer to make the theme functionality meet the needs of themeforest customers?