The macOS build is available in TestFlight. But when I go to App Store Connect to prepare it for submission, I don't see any macOS version in the "Build" section.
Selecting any option will automatically load the page
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I only see the output from the XCTest itself.
Xcode: Version 15.2 (15C500b)
This is related to feedback submitted at https://feedbackassistant.apple.com.