Maybe we could do like this in base-files.bb ?
FSTAB_HAVE_WIC = "${@bb.utils.contains('IMAGE_FSTYPES', 'wic', 'true', 'false', d)}"
FSTAB_WIC_UPDATER = "${@bb.utils.contains('WIC_CREATE_EXTRA_ARGS', '--no-fstab-update', 'false', 'true', d)}"
do_install:append() {
if [ ${FSTAB_HAVE_WIC} = true ] && [ ${FSTAB_WIC_UPDATER} = true ]; then
sed -i '/\/dev\/root/d' ${D}${sysconfdir}/fstab
fi
}
This would remove the hardcoded '/dev/root' entry if all conditions are met to add the root entry with wic fstab-update