We also have a CHERI-RISC-V specification (https://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-951.pdf), with support in CHERI LLVM, CHERI QEMU and CheriBSD, plus three open-source FPGA implementations (https://github.com/CTSRD-CHERI/Piccolo, https://github.com/CTSRD-CHERI/Flute, https://github.com/CTSRD-CHERI/Toooba) that span various parts of the microarchitecture design space, and it is the platform we use for our own research on architecture and microarchitecture. But for various reasons (e.g. proximity to the university, existence of competitive microarchitectures several years ago, ISA and ecosystem maturity, enthusiasm and interest on their part) Arm was the right partner for this program.