Casting/mirroring is a good alternative option. I have now tested it and it’s quite laggy. I have previously tested this on Apple products which wasn’t quite as laggy, but still not ideal.
Using the sideloaded APK gives use of Fire TV Cube 3rd Gen as a work around for any who chose or lack other options.
I personally preferred the option to hook my Core (Ubuntu Desktop) to the HDMi in on the Cube and switch inputs through the Cube remote.
Either options fixes the output to 24/48. Not an issue based on what I wanted to achieve. This is not my main system.
Screen rotation apps didn’t work well, or I didn’t find the correct one.