Alex Schmidt, a humor writer (formerly of Cracked and others) did this process for the bison emoji. I enjoyed his “miniseries” about it: https://www.bisonemojipodcast.com/

does the reverse notebooklm exist yet that turns podcasts into longform journalism?

Not that I know of. And I generally prefer written pieces to podcasts :).

The show notes for episode 2 have good references (no fun commentary though): https://www.bisonemojipodcast.com/show-notes