At least with Xcode 16 beta 5 it is possible to add the package as a local dependency to the demo project. The following steps give me the result I need: Open Project > Package Dependencies > Add package > "Add local" Optional for more convenience: Add package as reference: Drag&Drop folder of target from the package into Xcode 1. Action: Reference files in place 2. De-select target

Created FB14138815 for this issue.

This finally works with iOS 15 beta 1. As soon as the new model version is installed on the second device, it got all the changes populated in it. Thanks a lot for fixing it!