Looks like Chrome 91 (the same version we now use in Electron 13) provides read access to files in the clipboard:

https://www.chromestatus.com/feature/5671807392677888

async function onPaste(e) {
  let file = e.clipboardData.files[0];
  let contents = await file.text();  
}

This would open the door to allowing a user to copy files from a local folder and paste into the explorer to copy (desktop) or upload (web) them there.

I think we already have a handler for pasting but it is scoped to operations within the file explorer only.