The easier, and more lucrative, method is to setup some sort of Premium/Patreon/etc. method where you can either listen to the podcast, with ads, for free, or pay $X a month to support the show and get access to an ad-free feed.
It's totally viable to have 10% of listeners voluntarily pay while 90% of listeners freeload. And there needn't be any NPR guilt trip about it because they're not blowing millions on office space and executives.
Any successful podcast can be a very financially successful business for a small number of people.