Just a note: this was requested many times, also in our support portal. So I guess we should at least consider adding this feature at some point.
I forum searched a request post, maybe I missed it.
What am I missing here?
Basically you got it all right.
90° Stereocube maps with Proper implementation for eye distance, the 8cm neck offset, eye conversion distance... Etc.
Sure you can do camera rotation via script, but you lack the control you are used to otherwise.
UHD is the smallest of problems... Denoise will create major seams, no matter how well or clean it is handled.