This is the exact thought I had as I saw this post.
I'm currently building one out of an ammo can with a raspberry pi and an ungodly amount of squeezing and CAD work.
Very much inspired by this guy's buiild:
https://www.youtube.com/watch?v=-qo-nNeZTQE
My current progress:
https://i.imgur.com/k1WUoJb.png
Agreed. I've been obsessed with it. And I Made it extra challenging for myself by using a bigger screen, a whole whopping 9 inches. And then to add insult to injury I'm making removable batteries, a locking mechanism so it can be taken apart on the fly, a full mouse and keyboard, and a fan for airflow.
Eventually I might also add a GPS unit inside it too for the hell of it.