@jcabuco flash drive didn’t work for the 1040G3, but it did for the 1040G4.
What’s really confusing is that I pulled aside two 1040G3’s.
One of them is able to PXE boot and fully image with Secure Boot Off, UEFI On.
My guess is that there’s something within the BIOS of the 1040G3 that’s different from the other 1040G3. Ugh, at least I’m getting somewhere.