It's remarkable how much traction that article has gotten over the years; it's also cited by crosvm, rust-vmm, Firecracker, and many other virtualization projects.
I've shared that with a lot of people, because it's a great introduction to stepping through the abstraction of QEMU (or libvirt or whatever) and seeing what KVM can do. There's some good articles that start from VMx on up, which are fun too, but much more involved than KVM.
In general, this is a kind of technical content I'd like to see more of: here's a lower-level API, what can I do with it?
I enjoy such articles as well, especially when the lower-level API is something that most people only use through one piece of complex high-level software.
Similarly, it's fun to study containers starting with "unshare" and "clone".
I do like here that the author here went beyond minimal hello world and also showed how to boot linux