Thanks for the awesome bookmarket! It's very good 😊

Most of my work is with WordPress, which offers some standard but generally incorrect sizes attributes out of the box, so this bookmarklet is very helpful for figuring out what the expected sizes attribute should be.

WordPress also generates a variety of image sizes out of the box, but they may or may not be sufficient for srcset. An awesome enhancement to this bookmarklet would be to provide recommended widths for srcset images.

This is probably the preferred approach: GoogleChrome/lighthouse#11593 (comment)