In .NET 6.0, we will be adding support for new platforms including iOS, Android, macOS, iPadOS, and tvOS. As support for these platforms is enabled, we need to inform the Platform Compatibility Analyzer of which APIs are specific to those platforms and which APIs are unsupported on them.

To accomplish this, we need to apply [SupportedOSPlatform] and [UnsupportedOSPlatform] attributes throughout the .NET Libraries for these platforms.

We also need to ensure the SDK infers the appropriate <SupportedPlatform> items for projects targeting these platforms. This behavior already exists for Blazor apps where <SupportedPlatform Include="browser" /> is inferred.