Here's what I think I've learned now that I've been through the setup process for the native Home integration: I can expose devices from HE to GH, but I cannot expose devices from GH to HE.
Is that right?
In this case, it's a switch for a powerstrip. I also have a Google Nest Doorbell which I'd like to be able to grab the video from. I saw a comment about that that it was possible if you can find the video URL, so I'll dive down that rabbit hole in the coming weeks.
You are correct about it being a one way integration. What you can do is create a virtual device to share with Google. Then set up a Google Routine so that the virtual device and the Google only device match. This way Hubitat controls the virtual device with its automations and Google controls the actual device.