There are a few things you need to keep in mind before you start moving your Google Photos over to iCloud Photos. First off, restrictions apply to both your Apple and Google accounts. Your Apple account shouldn’t be a child account or a Managed Apple ID account. If your Google account is a child, work, school, or org account, you also can’t use it to transfer data to your Apple device.
Another important thing: iCloud Photos doesn’t support every media file type out there. You can only use JPEG, PNG, HEIC, GIF, BMP, and TIFF files for photos — as well as MP4 and MOV files for videos. If, however, the service detects any unsupported files in your Google Photos, they will still be transferred over, but to your iCloud Drive — not your iCloud Photos.
So now, what happens when you transfer your Google Photos to iCloud Photos? The process actually only copies your data from Google to iCloud. This means you get to keep your photos and videos on Google Photos. Once your media is successfully transferred, they’ll still appear in their original resolution with their original metadata, such as file name, date and time taken, and location.