Maybe a sort of notes function. You hit a button, at the point you want the note, which puts a timestamp after which you can add a few words describing it. It could also favorite the episode. Ideally the timestamp would be clickable and take you to that point. Obviously that would not be a big deal.
If more podcasts were really good about show notes, this function would be useless.
Edit: I’ve thought about hand written notes, but then the data needed are in two spots. It’s just less efficient.
Also example of the timestamp would be YouTube. Like how you can link to an exact spot.