Note that you can do without the skopeo call.
DOCKER_IMG="$(incus config get ${1} image.description | sed -e 's/^docker.io\///' -e 's/ .*//')"
SHA_LOCAL="$(incus config get ${1} volatile.base_image"
SHA_REMOTE="$(incus image info docker:${DOCKER_IMG} | grep ^Fingerprint | cut -d' ' -f2)"
This will basically do the skopeo inspect
call for you through incus image info