What thermostat modes are supported in Google Assiatant?

I have written a virtual thermostat with some custom modes beyond Heat/Cool/Auto.
I can’t activate them through Google Assisant, and it shows the thermostat as turned off.
Can anybody clearify what modes are supported in ST to GA integration?
I think some of the defined modes in the API such as “rush hour” “eco” are not supported as well, what gives?

The limitations are most likely in what commands Google chooses to support.

Seems like that’s the case for third parties. Wonder if Nest gets perferential treatment from Google.