In order to fully test this, I’d suggest finding a 64-bit version of linux for the Pi4 and attempting to run dolphin on it. I think there are 64-bit Pi4 kernels available for Ubuntu, Arch and Gentoo.
The programs get bigger when you switch from 32 bits to 64-bits so it will probably require a 2GB Pi4 to run 64-bit Batocera. I don’t have a Pi4 yet so can’t do it myself.
The Pi4 is available with more than 1GB of RAM so supporting a 64-bit version of Batocera makes sense.
Nicholas, will we be getting 64-bit Batocera for the Raspberry Pi4?