You can actually (if I understand your observation correctly). My teenage son pointed this out to me, as I would never have noticed it.
View attachment 546561
If the Tunein content is a podcast, it will have a hamburger icon to the left of the title when it is the active content. In the screenshot above, ABC NewsRadio is Tunein, but not a podcast. So no icon. Tap the hamburger icon and the episode list will open in the elusive full size view! From here you can play any episode as per normal.