Hello.
I hope this it is appropriate to forward this here but I talked to people about the ATUSB dongle at RIOT summit and some sounded as if they would be happy to have it available again.
It would be more of a development tool used for monitoring from Linux or testing a border router without embedded hardware like the Pi.
If you have interest please use my private stefan@datenfreihafen.org address to reply.
regards Stefan Schmidt