I want to comment on the previous Q&A item, but it's already closed. The accepted answer doesn't work for me.
I see "invalid child element" schema errors for rescap:Capability elements no matter where I put them in the Capabilities list, relative to plain Capability, uap:Capability, and DeviceCapability. I have this for the Package attributes in AppxManifest.xml
<Package xmlns = "http://schemas.microsoft.com/appx/manifest/foundation/windows10" xmlns:uap = "http://schemas.microsoft.com/appx/manifest/uap/windows10" xmlns:desktop4 = "http://schemas.microsoft.com/appx/manifest/desktop/windows10/4" xmlns:uap10 = "http://schemas.microsoft.com/appx/manifest/uap/windows10/10" xmlns:rescap = "http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities" IgnorableNamespaces = "uap desktop4 uap10 rescap" >
I notice that I can use DeviceCapability with rescap:Capability Name values, but only because there's no schema validity check on the value.
<DeviceCapability Name = "userSystemId"/> ultimately seems to have the desired effect.