Libreboot 9020 SFF running U-Boot UEFI payload. I was able to boot the OpenBSD installer perfectly, install it *with GPT partitioning* (fails in SeaBIOS), and boot it, perfectly.
Puffy UEFI is very much a thing in the next Libreboot release.
This is using the new "SeaUBoot" setup, previously mentioned. Unless interrupted via ESC menu, SeaBIOS will auto-load U-Boot from the flash, which provides a 64-bit UEFI environment on x86.
This is thanks to the work done by Simon Glass for U-Boot on x86.