Hello, I stumbled upon your discussion because I had 80% of your issues for some days until I solved for my Quest 2! I followed step by step this tutorial: https://www.youtube.com/watch?v=nd9p8R7OOoA
Have to say that worked on a blank project, so… I guess my answer won’t be so useful if you have an entire game ready 
sometimes I recover much of the work by migrating the maps in a new project.
Hope you all solved your packaging errors in the meanwhile