A Picker selection navigates you to the screen selected. The project uses Variables and States and depending on the picker selection I change a button state to navigate you to the right screen.

Basic To Do prototype based on: https://www.sketchappsources.com/free-source/3625-basic-to-do-app-design-sketch-freebie-resource.html

A simple spaceship animation using 'Animate Item' & states. Design Source: https://www.sketchappsources.com/free-source/3673-rocket-illustration-sketch-freebie-resource.html

Going to a screen depending on a picker selection using states, variables and the 'Fire an items event' action