An update:
I replaced my Roku stick with the Express 4K+. During the Roku installation, I was able to verify that every part of my system (LG UHD TV/Sony receiver/Roku) is now running 4K/HDR10/60Hz. I reran the Apple TV video troubleshooting feature and it said everything is fine.
That resolved some issues. Nearly all the other 4K movies that previously played in HD are now streaming as 4K. However, the specific James Bond films I mentioned above continue to stream in HD, not 4K, and that's clearly a problem on Apple's side that can only be fixed by Apple. I let them know three weeks ago, and of course they have yet to fix anything.
https://developer.roku.com/docs/specs/media/streaming-specifications.md
Roku has nothing to do with the content. Roku has their own guideline, recommendation on streaming quality etc. I'm sure Netflix, Hulu, Disney, Amazon Prime Video etc, have their own streaming quality etc.
You could be streaming at the speed of light and the content will still looks and sound like sh*t.
