I remember when the 3DS was region locked (cartridges can only be read if the console is bought in the same country those games are from) meaning it’s a headache having to switch between two variants of the handheld (I had a Japanese 3DS XL and an American 3DS regular back then, alternating on each one depending on which game I wanted to play). The switch alleviated this by making the cartridges / console region free.
I remember I had to use an adapter to play US games on my PAL SNES to bypass the security chip. So the adapter has two slots one for the PAL Snes game for the security check and the other for the US or JP game you want to play.