Google Assistant SDK - Send commands to different targets

Hopefully my subject will stand out… After scouring many, many ‘hits’ containing “Google Assistant SDK”, I haven’t found any reference to my specific case:

I have a Google Home Mini, to which my Google Home app on my phone is ‘linked’ and, apparently, so is my HA (Home Assistant), through the SDK.

I also have another ‘device’, my STB (Set-Top Box), a Bell Fibe TV box (an Arris VIP7802, an Android TV box), which also has “Google Assistant” built in. The remote has a Google Assistant branded button (see image, below) which, once pressed, I can give commands like “Play Blues on Stingray Music”, “Tune in NBC”, or “Play CHOM on iHeart Radio App”.

My HA detects the STB, but shows only volume and “Cast” as options/entities.

How can I sent “commands” to this STB? I’ve closely read the documentation, but it seems to assume one has only one “Google Home” device.