It seems the largest delay was not manufacturing, but the ability to get beyond their Nov 20th lock down due to export restrictions. There is a massive back stock of iPhone 12's and Mac Mini's that have only last week started to leak out of Shenzhen, China. Many of those items left Chek Lap Kok, Hong Kong on the 3rd of December destined for the US. If all goes well many Mac Mini's will land in the US this week for delivery on the same.
The iPhone 12 Pro Max that I ordered and did not arrive, nor was it shipped (contrary to having a UPS tracking number from Apple), I ended up cancelling. Later that afternoon I received a conformation that the Replacement that I did not order was shipped and would be to me by that following Friday. It did arrive on Friday as shown, unfortunately the following Tuesday (12/1) I received another email from Apple telling me my new iPhone 12 Pro Max was due to arrive on 12/4. It seems to me like Apple and their Chinese mfg need to be doing a lot better on communications, and expectations.
Ps. Don't call Apple support because it is horrible. After five calls they (three ladies from India, and two from Atlanta - yes, they were actually from Atlanta, as I'm from Panama City and call tell the accent) effectively told me WAIT, and I could return one or more after they arrived. This was contrary to the order on Apple that informed me none of my orders were eligible for return as my 14 day period had lapsed (At the time I had not received anything from Apple, so the clock never started).