The magic was finding a copy of the dtb that was used as the basis for most OpenBSD support: https://marc.info/?l=openbsd-misc&m=169046816826966&w=2

So I can use that as the basis for some FreeBSD work, though it's clear some later board updates will eventually require updates once the dtbs for this board have settled.

After lunch, I'll hook up to wireless and try installing OpenBSD to the eMMC

You, too, can run #OpenBSD on a VisionFive2, if you happen to have one around. I wrote up notes on what I did and some of the resources I used to figured it out: https://gist.github.com/csgordon/74658096f7838382b40bd64e11f6983e

I tried to give credit to folks who tried this before I did and did all of the actual technical work so far, but if you think I missed someone, please let me know.

Next stop: driver development hell.