It's funny seeing this article pop up as I've been exploring getting back into the handhelds as well recently. My 9-year old has his old Gameboy Advance SP (those flippy things) but finding games for the GBA is just terribly expensive if you want physical. We're trying to avoid emulating or getting those 500-in-1 types of cartridges for ADHD reasons, but he wants to play Pacman which costs as much as a secondhand PS5 around here.

The PSP sits nicely in the middle of timing, or at least it feels like that. Way more modern, easier to find games for, and way cheaper as well (more stock). It feels like the PSP was one of the last handhelds that you could use offline, without having to mod or hack it.

Seems like you want a custom cartridge

They exist, e.g. https://www.coolspotgaming.co.uk/products/custom-game-boy-ad... ( I haven't used this service )

This seems like a good mid point between a $500 cartridge and having no friction between games