They do serve ads on podcasts. Not all of them though. It used to be that they were separate, so that you were shown a different “now playing” screen. I first noticed when it happened on otherwise ad free shows, like Lateral. Not sure if that’s the case now? Some of the podcasts I listen to jump in length from the episode list to the “now playing” screen, which is weird. Don’t know if it’s because injected ads or not though, or if they’re even from Spotify. I haven’t seen those ads that are on a new “now playing” screen in a while.

Wheel of Time

Especially the first book of Wheel of Time famously has lots of similarities with LotR.

And what’s stopping you from doing it anyway?