@taylorswift thank you for taking the time and effort to document your experience!
Massive +1 on the point regarding engagement with developers on issues with Swift Macros adoption (irregardless of whether the issues originate from Xcode or SwiftPM).
Just as a reminder to anyone visiting this thread, Swift Macros currently can add as much as 12 minutes of build time on Xcode Cloud primarily due to its dependency on Apple’s source distribution of SwifSyntax, and (to the best of my knowledge as of writing this post) there is no ETA for a fix at the moment.