Installing on weird hardware - UEFI boot to serial?

[mav]

Greetings, I had a friend give me some surplus Western Digital Sentinel DX4000 NAS devices, and I'd like to make one run opnsense if I can. They are basically just really barebones PCs that loaded their OS (Windows Server 2008) from the disks installed in the NAS (which seems like a terrible idea, but whatever, I didn't buy them.) These things are a decade or more old, and rather finicky - they have a serial console, but no video out at all.

If I boot the serial image, it appears to boot - loads the boot menu, allows me to select normal startup, and starts booting but hangs at some point. The VGA image actually seems to work fine in UEFI mode; it boots just like it should, runs through the whole process, and then of course I get stumped when the installer switches to vga mode. I get the text output about it switching to 800x600 display mode and then, of course, nothing.

One piece of advice I've found about these is that because the firmware was super cut down, booting in MBR has unpredictable results; the systems were designed to always boot in UEFI mode. I have successfully installed Debian on this device before, using the 'console' boot option and that worked well. It seems like there should be some way to make opnsense work, since I'm so close, but I'm running out of clever ideas.

Is it possible that any progress was made on booting UEFI to serial console? I see this thread from a year and change ago but nothing since. Alternately, anybody got any ideas for making the vga image output over serial instead?