https://developer.apple.com/wwdc21/10085 https://developer.apple.com/wwdc21/10085 Privacy Relay is also discussed in the privacy pillars video for a few minute

https://developer.apple.com/wwdc21/10085 https://developer.apple.com/wwdc21/10085 Privacy Relay is also discussed in the privacy pillars video for a few minutes, starting at 24m30s.