Google Photos for iOS was updated yesterday with official AirPlay support, adding the capability to stream photos and videos to TVs through Apple TV. Google Photos version 2.14 finally brings support for AirPlay to the app, almost two years after it was first launched. Prior to this release, iOS device users who wanted to "beam" photos and video to their TVs could not use an Apple TV as an AirPlay receiver.
Google Photos is quite a powerful app, with frequent updates in the past two years adding features like content-aware filters, visual search, and video stabilization. It's a free download from the iOS App Store.