This video could be helpful for understanding some things. It doesn’t go into HDR as much as it should, but it does explain that our uscales usually use just one method, while the professionals use different upscaling methods per shot sometimes. So AotC/RotS would benefit from a professional upscale, not to mention the less-compression UHD provides AND wide color gamut.
https://www.engadget.com/2019/06/19/upscaled-uhd-4k-digital-intermediate-explainer/
This video does a great job at explaining things. I’ve been doing a lot of research into upscaling footage, and there’s a lot of newer algorithms that are pretty exciting, such as AI and neural network driven upscaling.
Even I’ve very much advocated that even SD material, like many shows shot in video prior to digital HD, would benefit from profesional upscaling and other clean-up. Doctor Who has been re-releasing their classic series on blu-ray and even those manage to get more out of sub-HD material and allow for a cleaner, less compressed image.