The iOS deployment target for iOS and tvOS on both cocoapods and Carthage is 9.0 and 10.0 respectively, while the deployment target for iOS and tvOS on SPM is 11.0 for both, it would be better to match the deployment target for SPM to that of the other dependency managers.
Not only this, but there has not been a release cut for SPM support. So when you try to add as an SPM dependency, it fails to find the package manifest.
The iOS deployment target for iOS and tvOS on both cocoapods and Carthage is 9.0 and 10.0 respectively, while the deployment target for iOS and tvOS on SPM is 11.0 for both, it would be better to match the deployment target for SPM to that of the other dependency managers.