Can an app host a webpage based on app properties?

I am building an app and want it to host a simple HTML file with data from the app so I can cast it to a Nest Hub.

Is this possible?

Yes, HTML pages in the settings folder are publicly reachable. So you should be able to just place it there

https://<cloudid>.connect.athom.com/app/<app id>/settings/<filename>.html

For receiving data, you can for example poll a public web API endpoint of the app

Thanks, I will dive into that.