piCore defconfigs come from Rasperry pi. Typically things like onboard ethernet and USB controllers are compiled into the kernel. These are the 5 kernels built.
armv6) DEFCONFIG=bcmrpi_defconfig;;
armv7) DEFCONFIG=bcm2709_defconfig;;
armv7l) DEFCONFIG=bcm2711_defconfig;;
armv8) DEFCONFIG=bcm2711_defconfig;;
armv8_16k) DEFCONFIG=bcm2712_defconfig;;
It was based on the sorter.sh. But I use something local due to the way I build the kernel module extensions. I have a different initrd module list for each of the architectures, I had to make it separate since the initrd's had drastically different modules. They are now quite similar, if you are building around sorter.sh, that will work, but likely you will need to have
sorter_armv6
sorter_armv7
...etc..