Correct, back in those days digital photos on a phone were also non-existant, which would have made the many pages to transfer everything so much more convienent.

Golden Sun also had a feature where you could put your GS1 game into sleep (at a specific data transfer point), take out the cartridge, and replace it with GS2, and unsleep, to transfer the data. My 11yr old brain was blown by this!

Yep! Specifically, it can transfer all the important things in 16 characters. The medium option about four times as big to send exact stats rather than just levels; that seems like a lot of work for little benefit. The big one transfers every single item in your inventory.