There's a website and merch too, though I just listen for free on Castbox, which has a nice option to shut itself down at the end of the episode: https://www.nothingmuchhappens.com/kathryn
My go to for videos to put me to sleep were trains going through snowy mountains. I didn't see any on the site, but an example: https://www.youtube.com/watch?v=ygjw-n1bOnE
Jeremy Parish (https://www.youtube.com/channel/UCrIttXi0WgLXHI1poCk0D6g) has been my jam lately. His content is well done, his narration is articulate and spoken in a low-key academic voice, and the content is interesting but not _too_ interesting.
Zzzz!