On MacOS you need additional steps to mount the EFI partition.
$ diskutil list
/dev/disk4 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *7.9 GB disk4
1: EFI hassos-boot 33.6 MB disk4s1
...
$ mkdir ~/volumes/efi
$ sudo mount -t msdos /dev/disk4s1 ~/volumes/efi
$ # make changes to CONFIG/network/my-network
$ sudo umount ~/volumes/ext4