Here is the working config
# detect iPXE
dhcp-userclass=set:ipxe,iPXE
dhcp-match=set:ipxe,175
# FIRST STAGE: UEFI firmware -> iPXE using SNP
dhcp-boot=tag:fog,tag:!ipxe,tag:!maas,snponly.efi,10.20.192.13,10.20.192.13
# SECOND STAGE: iPXE -> FOG (give it the script directly)
dhcp-boot=tag:fog,tag:ipxe,tag:!maas,default.ipxe,10.20.192.13,10.20.192.13
Factory default.ipxe.
I think deleting autoexec.ipxe was the missing piece a la https://forums.fogproject.org/topic/17937/uefi-boot-kernel-panic-unable-to-mount-root-fs-on-dev-ram0/9?_=1768445663029? Unfortunately, I tried so many different things that I am afraid to try to reproduce the failure and not be able to get back to a working state.
Regardless, it was not a missing NIC driver as I originally suspected. Thank you for your help nonetheless.