ChromeCast 1st Gen:
ChromeCast 2nd Gen:
ChromeCast Ultra:
Chromecast built-in is a partner program, much like Roon Ready, for TVs and speakers.
PS: AFAIK is this partner program now obsolete for TVs respectively got upgraded to “with Google TV” for current devices. Users may run into issues too when trying to use those as Roon displays (no more the same feature set as with the old “Chromecast built-in”). I hope Roon Labs upgrades its integration to keep up.
Does your Nest Hub look like any of the named supported devices? Can you find it on Google’s partner program pages as a device with “Chromecast built-in”?
While it might show up under Displays in Roon, it is obviously incompatible (right now) and never worked so far:
And that’s it since Nov. '18. So there is still hope … there was no definitive “No” so far.