The NVIDIA SHIELD is a strange device. It has Assistant built-in, but it sometimes lacks features of other Assistant devices. You can also control the SHIELD from other Assistant devices, but it doesn't have all the standard Chromecast features. NVIDIA says "deeper integration" with Google Home is rolling out now, which may help to smooth out some inconsistencies.
Unfortunately, NVIDIA is pulling a Google here and has mixed in new things with old. Here are the examples NVIDIA included in its blog post. Keep in mind, these are all commands given to a Google Home, not the SHIELD's built-in Assistant.
“Turn on SHIELD”
“Turn off SHIELD”
“Open [name of app] on SHIELD”
“Set volume to 50% on SHIELD”
“Increase/decrease volume on SHIELD”
“Mute/unmute volume on SHIELD”
“Play [name of Netflix, HBO NOW, CBS, Viki, or Starz show] on SHIELD”
“Play [name of song] on [name of app] on SHIELD”
“Watch [name of channel] on YouTube TV on SHIELD”
on YouTube on SHIELD”
“Pause on SHIELD”
“Play on SHIELD”
Photos and Smart Home
“Show me my pictures from Egypt on SHIELD”
“Show me my pictures from last weekend on SHIELD”
“Dim the lights”
“Set the temperature to 72 degrees”
So, some of these are clearly quite old. Photo albums have worked on SHIELD since the early days, and you've long been able to play content by voice in YouTube. Netflix support came to Android TV devices last week, too. Google Home used to complain about turning the SHIELD on and off, but it worked sometimes. Now, it's officially supported. Volume controls work, and we think these are new. We're fairly certain opening apps on the SHIELD is new, as well.
NVIDIA says everyone should have the new features this month. If you restart your SHIELD, you'll have them within a day.