The most useless advice you can give a #podcaster who is begging for feedback is "Make what YOU like." Obviousely they like the subject they are covering, they are trying to work out what kind of things their audience would find useful. 1/2
If your a listener tell them what topics you'd like them to dive deeper into. If your not a listener let them know what would make you a listener. Podcasts are either Diaries, courses, or entertainment and all three require some degree of playing to an audience.