Not much relevance if you haven't got a Pixel, but may interest others that do, the current implementation of the free photo storage is defined by photos uploaded from the phone, regardless of what they were taken on, people may not have realised that.
To explain, Google Photos provides free storage for images in "high quality" but only Pixels get original resolution (others are subject to a 16Mb original size and will be resampled). This means that, if you have a Pixel and can be bothered, you can have free unlimited storage at original resolution of ALL your images (including 4k video) by uploading through your phone. To do this you need an OTG adapter with a card reader, OS will take over once it has discovered it or you can use ES File Explorer app or the like to move the images onto your phone and delete them when they are uploaded.