This human-readable summary of the Peer Production License is handy.
"The peer production license is an example of the Copyfair type of license, in which only other commoners, cooperatives and nonprofits can share and re-use the material, but not commercial entities intent on making profit through the commons without explicit reciprocity"
https://civicwise.org/peer-production-
licence-_-human-readable-summary/
@neil Am I missing something? What does the PPL offer that CC-BY-SA doesn’t?