TIL you can enter a photo description in Google Photos. Select a photo, click the Info icon, and a free-text “description” field is revealed. Not super sure what the description is to be used for, but I’m hoping to use it for photo captions.

Screenshot of Google Photos in Safari with the info plane reveal and a sample description entered just above the photo metadata. The sample description reads: This is a description. I guess it can be used as a caption if you want it to.