I would like to see this working in Chrome OS. Discourse is already a PWA, so the stars are aligning.
I would also like to be able to share things TO discourse. For example, if I were to select an image to share to Discourse, it would create a new topic with the image inserted at the top. The title of the image would then be put as the topic title.
I also know a lot of people who use Windows, so support for that platform would also be great. They want to use the native menu. It looks very clean.
The same can be said for macOS, although I’m not too sure how the implementation would work.
TL;DR: I want to be able to share files TO Discourse in all major operating systems (both mobile and desktop). Along with that, I would like to be able to share links FROM Discourse on all major desktop operating systems. 
Also, does Firefox and Safari support the Web Share API? I originally thought that it was only supported in Chromium browsers.