The NVIDIA SHIELD TV is due an update soon. The most likely candidate to fit this bill has gone through registration with the FCC, and has also just secured Bluetooth SIG approval. Therefore, there may still be time for it to be released this year
https://www.notebookcheck.net/A-new-certification-brings-the-NVIDIA-SHIELD-TV-2019-closer-to-launch.435962.0.html
Projected to come with 4k HDR? Its already supported...
As well as google assistant.