By the way, some minor kernel config bike shedding for ethernet - I have:

    # Ethernet fails as module
    PTP_1588_CLOCK = yes;
    STMMAC_ETH = yes;
    STMMAC_PLATFORM = yes;
    DWMAC_GENERIC = yes;

You can swap STMMAC_PCI for STMMAC_PLATFORM (I guess PCI requires PLATFORM?). I also added the MAC so ethernet is fully builtin.

In reply to @matthewcroughan:defenestrate.it
Is there anyone around who would be interested in trying to get NixOS working on RiscV boards?

Hi. I need to make an amendment to my project, otherwise I fear I will not be able to complete it.
I've started an initiative inside of the NixOS community, of people who have already made great progress on the VisionFive board, even without help from riscv.org. We need 10 boards. There are 10 very capable individuals in this initiative who would be fully able to implement this work, and will do wonders for RiscV support both on NixOS, and Linux in general, the scope of improvement they can bring to the ecosystem is far greater than just NixOS. These candidates already have great experience with modifying, bootstrapping and upstreaming support for RiscV, and are deeply embedded in the open source community. They are amongst the best able to accomplish this work, and they will very much spread the news about RiscV on their social media. The initial project proposal assumed that I would be doing most of the work, but this is no longer the case, as I have taken on more work, but if we can receive more boards, this project can be completed under the given terms.