Nice interview. I have been using Emacs for about 40 years, and I am getting a lot out of Petersen's book. He recommends reading the Emacs Manual - I mostly did that decades ago, and forgot most of it.
"He recommends reading the Emacs Manual" is basic and obvious that a lot of people miss it. I try to do it for all software that I use. I don't need to memorize it, but familiarity is helpful.
Even if I can't remember how to do X I know the piece of software I'm using can do X.
It’s very long and dry. I recommend balance it with installing some flashy packages like selectrum, company-mode, and eglot. The wonder created from using incredible packages helps fuel and direct the drudgery of learning the nitty gritty.
Ha. I feel the same about vi. I know enough to use it for basic edits if emacs isn't available, but I struggle with it.
In one of my first programming classes in school, the available editors were vi and emacs. The modal operation of vi kept throwing me, so I used emacs. Over 30 years later I have rarely used anything else. I had one job where Visual Studio was used. I tried using it with emacs keybindings, but eventually switched to using emacs in cygwin and only used VS to run builds.
Basically how to open, save and basic editing. I knew it was going to be slow and mildly painful to learn but I wanted to learn Clojure (since moved on to Common Lisp).
I used Vim for several years and would still consider myself very novice. I don't dig into anything for the sack of digging. I learn just enough to do what I need to do. When I need something new then I look it up. Same thing with Emacs, I've been using it for 4 or 5 months. I enjoy it and it lets me work with Common Lisp so I'm happy.
VS Code has many pleasant properties, but its lack of respect for user freedom is a real turn off. Also it is considerably less conveniently extensible than Emacs. That however is definitely a double edged sword and there are valid reasons to go with a less customizable tool.
It’s not so much the particular extension language as it is the design philosophy. JavaScript is considerably lispier than most squiggly brace languages.
I learned it by using it to do a project in college in Common Lisp using SLIME. There wasn’t really a good Lisp environment for the editor I was used to before that (visual studio) so o had to power through.
Anyway, I recommend his book.