You might enjoy the fact that my early critiques to Qubes told Joanna Xen was a security problem she should've avoided in favor of separation kernels w/ user-mode Linux virtualization, user-mode drivers, and a trusted GUI subsystem. She vigorously argued against that on the mailing list. Years later, they now have some kind of trusted GUI schemes and she's griping at Xen for being insecure. I don't know if she reduced privilege of drivers or has since learned why that's a good idea. The 180 was hilarious.

I'm sure their product will have plenty more vulnerabilities as she lacked foundational knowledge in building secure systems. Meanwhile, with little labor, GenodeOS was incorporating many well-designed components from the start such as L4 work, Muen, seL4, Nova microhypervisor, Nitpicker GUI, etc. They're still alpha quality due to clean-slate work needed in that approach but moving on steadily. Check them out.

Note: For appliances and embedded, JX Operating System is also worth Googling. Remember that JVM can be replaced with Ada, Go, etc runtime or Rust.