It's strange that this isn't a thing. Commercial pilots occasionally have a chief pilot observe their performance during flights and make suggestions on improvements.
This absolutely should be more of a thing in any healthcare setting too, not just surgery. Not just something that happens during residency.
I wonder how coaching can be applied to software engineering. As a developer, I undergo code reviews and participate in design discussions, but there isn't a lot of oversight or feedback given on the actual development process.
You may enjoy reading the book "The Coaching Habit" which, while not directly talking about coding and code reviews, has a lot of good guidance on how to bring a coaching mindset to them.