Android
You can add a snippet to your 1SE app for Android directly from your Google Photos library.
The Google Photos API will undergo changes starting April 1, 2025.
iOS
It's not currently possible to select media from Google Photos directly within the 1SE app for iOS.
If you want to add media from the cloud via Google Photos, you'll need to download it locally by going into Google Photos and selecting "Download." Once downloaded, this media will be available in your library when you choose content in 1SE.