You will need to install a user script manager extension to install this script.
Combined mew's dark with many fixes with full res images and enabled right click
you can find skin that removes login requirement in profiles here: https://greasyfork.org/en/scripts/420256-instagram-removed-login-requirement
but with a recent change you can view pictures (without account) with the middle mouse button
in stories right click is accessible at the right edge of the video.
Non-Dark version here: https://greasyfork.org/en/scripts/419884-instagram-full-res-right-click
I don't actively use Instagram so report bugs or additions as comments