Just putting the idea out there :).
I now have a kid but she is too young still but I am definitely going to be getting her into building Kano devices.
https://kano.tech main page with all the devices https://world.kano.me their community for kids and learning
I've got the Pi booting basically straight to Love2D (really it's a combo of carefully choreographed splash screen, LXDE wallpaper, then an autostart of the actual Love2D UI which makes it seem like the Love2D UI is in control from boot) and it's all worked very smooth.
I feel like this setup would work well for custom UIs (especially if you're not as obsessive about the polish as I am and can tolerate a few flashes as X boots up). There's nothing specific about Love2D which makes this work other than being a nice way to write code that runs smoothly on a Pi, but I like it :)
Load81 might be of interest for this as well, it’s a commodore-like console interface for Lua, made by antirez: https://github.com/antirez/load81