IOS 13.0 build 17A508

Yukon 17A508 is an InternalUI build of iOS 13, judging by the file dates, it was compiled 21 hours after WWDC 2019. It appears to be a full build and not desense due to the number.

Findings
This build references to an accessory called "B389, this is the codename for AirTags. It also refrences "D79" which is the codename of the iPhone SE 2020 model.