I wrote a "box model" UI library to meet my needs for building menus/dialogs, and decided to polish it up and open source it:
It allows for flexible layout in the style of CSS Flexbox, box styling, text layout, and basic interaction via things like tabIndex.
I hope it's helpful for other folks!
Can confirm; very helpful!! I made a little confirmation prompt:
You call confirm(“message”, callback) and it handles inputs, in case anyone wants a little example: Playdate confirmation dialogue/input prompt with playout library (https://github.com/potch/playout) · GitHub
My example even uses the sprite helper! So many features 
Updated the gist ^^ with a prompt function that uses the sdk’s keyboard. Call prompt(“message”, “value”, callback)
Nice! Gonna be using it in my game