It blows my mind that this is what the company ended up using... Why? Normally the price is the factor that chooses what part is used in a system. Surely it would be cheaper to use literally any regular screen than to retrofit a Gameboy SP topcase into your design...
Maybe one of the devs used a gameboy screen to develop on personally, and made a prototype of the product using the knowledge he already had using the gameboy. As a deadline approached and they ran the numbers comparing development cost of a new display system vs sourcing tons of gameboy screens, and gameboy screen sourcing came out cheaper with their predicted number of orders. Or maybe a dev thought it would be funny, I don't know man.