Initially my IP was showing up all over the US. My guess is they were working on the logic and adding more CDNs. So far I've seen Cloudflare and Fastly.
I wonder if you could abuse this to bypass ACLs on Fastly customers that block direct origin traffic.
Money solves a lot of problems. Fastly already has a geographically diverse set of servers, so I could see them building a feature like this just for Apple (at least initially).
Great point about the ACL.
I was very surprised when I checked and saw Fastly on my iPad as I wasn't aware Fastly had any similar product, in my mind they are (were?) strictly a reverse proxy CDN.