I said a separation kernel like the FOSS projects and commercial products dating back to 2005 I told Joanna about on Qubes mailing list which were compartmentalizing things on security-focused kernels. Aside from small TCB, they have optional mitifations for storage and timing channels. Aside from isolation, a standard practice on embedded side was including safe subsets of Java or Ada running right on the kernel to implement specific components more safely. So, basically just what was standard, deployed practice in high security over a decade ago.

Optionally, I also pointed out people interested in developing solutions have options available now for safety or security on CPU side, too. They can do software, hardware, mix of both, whatever suits their purposes.