Joking aside. We are aware the issues with the new builds. Can't give you a time frame yet for when they will be resolved. And, to be clear, right now our priority is working on features on macOS not related to Big Sur (e.g. Education Profile).
FWIW, Apple doesn't give vendors any special early access to builds. I'm not complaining, just explaining that when you install a new macOS beta we have just seen that build for the first time as well. I'm an Apple fan: they are bold in making big changes, but as a vendor supporting them it means that it can take a while to adapt to those big changes.
Since you mentioned "zero day support", I wanted to clarify a point lest there was any confusion.
We certainly have access to Apple beta builds (which is how you develop and test to support a new OS release on day one). What I was trying to say was we get those beta builds exactly when everyone else gets them. So, if there is a breaking change we encounter at the same time you encounter it.