[Libguestfs] Specify partition when using virt-customize --copy-in, copy file to boot partition

Using virt-customize of libguestfs, I can copy a file from the host to the root partition of an image like this: virt-customize -a 2023-02-21-raspios-bullseye-arm64-lite.img --copy-in cmdline.txt:/boot/ But the image also has a boot partition (FAT) and I want to copy that file to that partition instead. Is that possible using virt-customize?