This Progressive Web Apps is an experiment using Share Target Level 2, allowing it to appear in the share sheet and accept images. If you install this app using the "Add to home screen" prompt, it will add an "Edit" option to your share sheet, allowing you to do some basic image editing in a web app!
I got tired of having each app always save a copy of my image any time edit an image. Taking a simple screenshot for a one-off share can result in 3 or 4 images being saved and you have to then go delete in order to clear the clutter. And solving this problem with a small web application is just cool! With newer version of Android (and Chrome 76+), you can now take a screenshot by summoning assistant and selecitng "Share screenshot", crop and markup in this app, and share it out, all without ever saving an image. Neat!