When you need to upload a file (an image, an audio file, a video, etc.), instead of the "Choose File" window immediately opening, there should be a small window where you can pick one of the 3 most recent downloaded files of that type, or whatever is copied in your clipboard. If that's not what you're looking for, with a press of a button below, you can open the bigger "Choose File" window with File Explorer.
This is how it works with Opera GX, and I hope to see it in Firefox. There are almost no ways to get a file from your clipboard into an upload link, so this addition would make everything SO MUCH EASIER, and may even attract some Chrome users.