Disable html embedding and paste multiple links in canvas?

What I’m trying to do

Hello I have list of urls that I extracted from firefox tabs using an extension. The urls have the following format (:
file:///file path (for pdfs)

I would like to be able to paste the links in a canvas all at once. I can’t and if I copy/paste one at once it only works for urls with https and http prefix.
There is some plugin/addon for doing this?
Also, there is a way to disable direct page embeding? The list of urls I have is very big and it will grow even further, so, I only want a page thumbnail rendered, not the actual pages being processed and consuming cpu power…

Things I have tried