Before the pandemic the store would run out of items one or two at a time and restock them fairly quickly. It seems unlikely the pandemic and the company’s ability to keep their store stocked are unrealated.
As for best estimates on the settings for non-proofgrade, they are the proofgrade settings. Acrylic is acrylic, it’s only the thickness that really matters. The same is true for vegetable tanned, non-dyed leather. I’ve seen postings around here about the equivalent weight (how it is sold everywhere but here) for medium, thick and thin. The proofgrade plywood is mdf core plywood with a thick, nicely matched, veneer. The settings for other mdf core plywood should be the same for the same thickness. There are settings in Beyond the Manual for true Baltic Birch. I find 1/8"/3mm BB cuts similar to proofgrade Maple plywood. The proofgrade hardwoods should cut the same as non-proofgrade of similar thickness.
Glowforge has made it very clear over the years they don’t support non-proofgrade in nearly any way, pandemic or no pandemic. Some people here agree with that, many others do not, I can see both sides of the argument. As I don’t use much proofgrade I generally steer clear.