This uses the Rapid7 1500 (~1,327 unique domains for 1,500 listed organisations) organisations corups and identifies valid DMARC records from their primary/vanity apex domains, then builds a network of who processes their RUA reports.
Live view (updated weekly) — https://hrbrmstr.github.io/weekly-dmarc-grabber/index.html
Mostly done to finally play a bit with GHAs.