just the nexus player i believe
Nexus Player only, on which it is notably buggier than Marshmallow, with many glitches and lags in the UI, the new Settings UI is awful, and WiFi is far more unstable. It also broke some apps that have yet to be updated, without bringing much new to the table, so all in all this compulsory update to the NP was not exactly welcome for me personally.
Nexus Player; that's it. SHIELD's is in beta/pre-release, and they're taking signups ATM to test it before RTM.