Copy image from Gallery app or a file browser into a paste target of a web site

A website allows you to copy an image on the desktop (CTRL-C) and paste it per normal CTRL-V into an HTML element for **upload**. How can the same be done on Android, either in the Gallery app, Amaze File Manager, or some other app? The website takes the image from the clipboard on the desktop, but it seems there is no way to get an image into the clipboard on Android. With text, it works as expected. I tried 'share', but no browser is provided as a share target. If that could done, it might be an option too. Edit: As mentioned in the first comment, the question https://android.stackexchange.com/q/244586/44325 is related, but this is about copying an image from one website into another. I'd like to copy an image already from the device into the browser. This seems to require the image to be in the clipboard and so far I could not find any app that puts an image into it.