>'then we'll just ship your machine production'

Minus the kernel of course. What is one to do for workloads requiring special kernel features or modules?

Those are global to the machine; generally not an issue and seccomp rules can filter out undesirable syscalls to other containers. But GPU kernel/userspace driver matching has been a huge headache; see https://cacm.acm.org/research/a-decade-of-docker-containers/... in the article for how the CDI is (sort of) helping standardise this.