One of Google Assistant's best features, in my opinion, is that it can play several types of ambient noise. It's a wonderful feature to have on Google Home, particularly for folks living in noisy environments. But the functionality extends to any Assistant-compatible device, and you're even able to download the sounds for offline listening through the Google Podcasts app.
The method here isn't particularly straightforward; you can't find the sounds by searching inside the Podcasts app. Instead, you have to ask Google Assistant to play a sound, then tap the Open button that appears (or the playback notification). From there, touch the bottom bar, then the info button. Finally, from this screen, you're able to download the sound, which will then appear in your list of downloaded podcasts.
In case that was a little tricky to follow, here's a GIF:
The convoluted method of accomplishing this makes it seem like the feature might not be entirely deliberate; ambient sounds have always played through the Google app, which Google Podcasts is technically a part of. Still, the functionality could be useful on a long flight or any other time you want to drown out noise sans mobile data.