Also if I put a link into the page with the about:reader uri scheme, it does not work (opens blank page if I open new tab, does not go anywhere if I click on it without opening new tab)

I suppose it might work if I put it into an extension of some sort, if not then I think to make it work on Windows it would be easiest to have an AutoHotkey script that prepended about:reader?url= on the address line and pressed enter for you.

I have as yet to find a worthwhile AutoHotkey competitor on Linux or MacOs.