hey, @adam... did you hear about NPR's announcement of RAD?
"Podcasters mark within their audio files certain points (quartile or some time markers, interview spots, sponsorship or advertising messages, etc.) with RAD tags (ID3 tags) and indicate an analytics URL. A mobile app is configured to read these RAD tags and when listeners hit those locations in the file, bundle and send anonymized information to that analytics URL. "
Curious your thoughts...
https://radioink.com/2018/12/11/npr-announces-podcast-measurement-system/