It's almost done, and I do plan to spend a little effort promoting it when it's complete, but it's been a great focus for me even if no one ever reads it.
I use a fair bit of infrastructure at my job that was set up by others. It was nice to go through the practice of setting it up myself.
I learned a good bit, but also it's nice to have all this knowledge written down in a place not owned by the company I work for. If I use GCP at future jobs I'm sure I'll reference this book myself.