Well... Book clubs, study groups, fraternal organizations, etc. have agendas that structure conversation. I've found this useful for even 1:1 conversations with friends.

Naturally, it's possible to take this too far; letting the conversation flow naturally before occasionally snapping back to the agenda is both more enjoyable and often more productive.

...this is also a common podcast format.

I have never heard the phrase "private podcast" used in this sense before (vs the group / company internal sense), but... I kinda like it; sets up some potential useful expectations!