Sabrina, I mentioned in my response above that we DEs tend not to recommend beta readers as much as we should; we also don’t recommend the practice of investigating how other authors do it often enough. That’s a great idea; if the author literally takes notes about how their favorites authors present various characters, they are likely to learn something useful! Often authors as readers are passive consumers, so being more active/critical about what they’re reading is one way to learn craft.
I like how you connect show v tell to deep perspective. The POV character can’t know what other characters are thinking and feeling but they can notice what the other characters are doing! They can interpret these actions correctly or incorrectly but they can’t know for sure.