Yesterday, Microchip announced the first FPGA to have a hard RISC-V CPU core; the PolarFire SoC. Looking at the power consumption graphs on the product page, the chip appears to use 50% of the power compared to a similar-sized FPGA SoC with an ARM CPU.
The 5 chips in the SoC family are capable of running Linux and have between 25k to 460k logic elements (LEs), DDR3/4, LPDDR3/4 interfaces and between 4 and 20 transceivers running at 12.7Gbps.
If you can work with BGAs with a 0.5mm pitch, there are 25k and 95k LE versions available in a 11x11mm sized package. There are other options available with 0.8mm and 1.0mm ball pitch. You can see a summary of the product family here.
Update:
Microchip have announced the release of a dev board for the SoC, too. It’s called the MPFS-ICICLE-KIT-ES and costs $489. You can find more details here:
https://www.microchip.com/en/pressreleasepage/industry-s-first-soc-fpga-development-kit-for-risc-v