Upload image from URL into file upload prompt / input field using javascript?

I’m attempting to upload photos by stored urls on poshmark (https://poshmark.com/create-listing) but can’t figure out how to. The input type=”file” making the file upload prompt come up. Is there anyway to send urls to this and click Open?

I found this: https://medium.com/@dev_agam/automate-file-upload-with-chrome-extension-7ee6989d58e9 but can’t seem to figure out how to use the code.

I’m self taught and want to learn so the lengthier the explanation the better! Appreciate the help!

I haven’t tried much of anything I’ve just been researching and it seems most people claim it’s impossible but found a recent answer linking the article above.