Here is an AI chip:
https://hackaday.com/2018/10/08/new-part-day-the-risc-v-chip...
It's an interesting proposition b/c they using RISC for the core, but the APUs are custom - so they can create some lock-in there for themselves (without lock in it'll just be a race to the bottom with razor thin margins)
And here is RISC-on-an-FPGA in a nice package. It's very Chinese hobbyist oriented https://www.cnx-software.com/2018/09/04/licheetang-anlogic-e...
Both those projects are by Zepan. That guy is a machine
But I'm not quite sure what's holding up general purpose CPUs (even just something crappy/good-enough).. The way I understand it CPUs aren't just beefy microcontrollers and they require some extra onchip hardware, but no one has done that yet for some reason.. Maybe someone knows better :)