Adds new device support, and security patch through April 2021.
Details:
Edit: Not sure why it required 2 installs, but this happened on both of my Nvidia Shield Pro 2019 models.
Edit 2: Actually, it looks like this update is bugged and is not properly installing, even after a number of attempts. Probably best to avoid this for now.
Edit 3: Follow the advice here if the update is not installing for you, this worked for me. Seems to be buggy with 2019 models:
Google tv > android tv.