Clients, menus, firmwares and all other flashcart related files for GameBoy Advance. Remember to also check the DS Flashcart Files section as many GBA capable carts were released with the DS in mind.
I may try the new ram site, and download more RAM to my Switch. Not sure if ddr3 is the right ram
for it tho. Edit- no it uses floppy Ram, just like @AncientBoi