> There's no open source network, graphics, peripheral and GPIO hardware that can be cheaply plugged into a synthesized design that can be sold at the price you want.

Why not PCIe? Aren't there already a bunch of design/validation/verification tools for it? A RISC-V CPU with just a bunch of PCIe lanes (and a couple of channels of fast DDR4) coming off of it (and maybe an IOMMU) would be a lot easier to integrate with existing hardware, rather than trying to recreate open-source equivalents of modern GPUs and network hardware.