I've interviewed hundreds (maybe thousands at this point?) of candidates in the course of my career, and as much as I think giving feedback at the end of the call is a great idea, I personally would struggle with doing it in a way that was actually useful to the interviewee. Because unless it's a hard "no" (e.g. someone is obviously lying about their experience), I almost always need to ruminate on the interview afterwards before I can write up useful feedback. Sometimes it's the act of writing itself that helps me form a coherent recommendation.

This is also why I hate interview processes where my co-interviewers want to debrief immediately, or when I have a recruiter breathing down my neck as soon as the call ends.