I haven’t investigated whether an API exists to pull in Google photos. But if you were able to get a URL to the photo, I think you could use Conditional Image Server to “serve” it up from Hubitat. You could set up rule machine to pull in a new picture every minute or however often you liked.
As is, I think that solution would require the image to be at a “publicly accessible” URL, which could of course be a “secret” URL only you know. If it were possible to have an authenticated session into Google photos, the same idea could be used on top of that for secure access to your photos.
Edit: having looked now into this a bit more, the API exists for this to work. I think it is possible. It is just a matter of how hard it would be to do it. Particularly the authorization for the API is a bit involved it seems.
@dkilgore90 might be able to speak to how easy it would be to develop an integration with Google photos, as the developer of the newest Google Device Access integration.