[Boerworz]

The "Get ready for iCloud Private Relay" session[1] from this year's WWDC makes it seem like there will be a publicly available list of IP addresses used by Private Relay:

Private Relay guarantees that users can't use the system to pretend to be from a different region, so you can continue to enforce region-based access restrictions. Details about the proxy IP addresses will be available as an article associated with this session.

Though I haven't been able to find the aforementioned article.

[1]: https://developer.apple.com/videos/play/wwdc2021/10096/

[banana_giraffe]

Here's the article:

https://developer.apple.com/support/prepare-your-network-for...

And their IPs, as mentioned in that article:

https://mask-api.icloud.com/egress-ip-ranges.csv

Seems to be mostly Fastly IP addresses right now, but I'm sure that'll change over time.