Omega2+ No Factory Image

I am building LEDE / OpenWRT v17.01 for the Onion Omega2+. (I know. This is an ancient version, but I have customer requirements...) Doing the conventional "make" process works fine, except it only generates the sysupgrade file (lede-ramips-mt7688-omega2p-squashfs-sysupgrade.bin). It does not generate the complete "factory" image (which I expect to be something like lede-ramips-mt7688-omega2p-squashfs-factory.bin).
I checked the menuconfig and did not see an option for this.
Am I missing something?
Thanks!

Nothing unusual when I check https://downloads.openwrt.org/releases/21.02.1/targets/ramips/mt76x8/ for Omega2 images. Plenty of devices only need sysupgrade images - that usually means either their recovery happily accepts it or they use some OpenWrt fork that offers sysupgrade functionality.

Support was added in commit ab90f15c89da6aeadf8b95554fcd8ab8e3f433d0 by someone from Onion themselves. I'd first check your original installation for the presence of the sysupgrade functionality and if not ping that person.

@Borromini thanks for the quick reply! I guess it makes sense. I'll see if I can actually just do an upgrade rather than a full factory program.