Useful article on editing with Snapseed by Jo Bradford:
amateurphotographer.com
She's written a couple of books on smartphone photography, so she mentions them several times in the article, but it's not obtrusive, and there's some good info there. For example, she describes how to create a custom vignette using the Curves tool and masking, which was new to me.
(Oddly, though the article is clearly by Jo Bradford, there's no byline at the top, and the bio at the bottom is for someone else.)

How to edit photos with Snapseed
Snapseed has been around for a while, but it’s still a superb free app for editing photos. Jo Bradford shows how to get the most from it

She's written a couple of books on smartphone photography, so she mentions them several times in the article, but it's not obtrusive, and there's some good info there. For example, she describes how to create a custom vignette using the Curves tool and masking, which was new to me.
(Oddly, though the article is clearly by Jo Bradford, there's no byline at the top, and the bio at the bottom is for someone else.)