https://gbadev.net/gbadoc/interrupts.html

> It is possible to switch cartridges and have the routine resume execution on a completely different ROM.

That would have been a heck of a game mechanic back in the early 2000s! Maybe I never saw it because game developers were tired of the “please insert disk 2” of the Playstation era. But it feels like a gimmick a Metal Gear Solid game could have used.