I did contact Microsoft about their companion devices framework and got a response from Anoosh asking for more information, but havent heard any more since then. I assume I'll get a response that either says that its not suitable for what we're doing here, or that we can get access to this framework. That'll presumably be win10 or higher so I'll keep working on the old solution anyway. My new NFC ring arrived today so I'll finish off the code and use that to register the new device to test the process and then upload it all to github.