Yes: on Android you can pick photos and videos from Google Photos when adding a snippet, and on iOS you download them from Google Photos first. Here's how it works on each.
Android
Since April 1, 2025, Google Photos works as a picker: you choose the photos or videos you want each time, and 1SE only sees what you picked. 1SE can't browse your whole Google Photos library any more, and the picker doesn't sort by date.
To browse by date, pick from your phone's Gallery instead.
If a video isn't on the phone, download it from Google Photos to your device, then add it in 1SE from your library.
Auto-Fill reads what's stored on your phone, so it isn't affected.
iOS
It's not currently possible to select media from Google Photos directly within the 1SE app for iOS.
To use something from Google Photos, open Google Photos and select "Download." Once downloaded, it's in your library when you choose content in 1SE.