Elon completely leaving out the real reason. His losing bet on 4680 is why Tesla doesn't have enough US battery supply. They had two years to prepare for the EV tax credit qualifiers. That is why Model 3 doesn't qualify.
This one I will disagree with you:
4680 was not a bet. It was and is an effort. And, not only did Tesla work it on their own, they managed to convince other battery cell manufacturers to work on building cells of the same dimensions...and those other manufacturer factories aren't online yet either. And, Tesla didn't stop buying a wide array of other formats of cells from many other suppliers, so it's not like the 4680 somehow signaled Tesla didn't want other cells anymore.
Even if 4680 is behind some assumed schedule, I don't know what other battery supply could Tesla have realistically brought online in the US by now. Tesla simultaneously announced their 4680 goals while also saying they would buy any and all qualified cells from suppliers. Tesla indicated they would need terrawatt hours of cells per year. They stated huge numbers for their projected need for cells, but they can't "make" suppliers build more factories and they can't just wish their own technology development and production ramps to magically go faster.
The only thing I can really think of is, I guess, Tesla could have bought other battery cell manufacturers' patents and trade secrets and factory designs, and just copy-pasted those in massive numbers in the US. Something tells me that isn't exactly realistic -- if Panasonic or LG can't scale or copy-paste their own factories fast enough, I'm not sure how Tesla would be able to buy the necessary patents and trade secrets from them, and somehow come out ahead trying to do exactly that.
We know Tesla buys a wide variety of cells from suppliers in China. Obvious message from Tesla about their demand for any variety of qualified cells.
We know Panasonic is still ramping up Giga Nevada 2170 production. They have always been slow/hesitant to ramp...but I don't see any sign that it is Tesla holding them back at this point. I'm sure Tesla would love to be able to have enough 2170's from Nevada to fill all the Model 3's and Y's built at Fremont...but it's Panasonic that hasn't ramped up to meet the obvious demand.
We know Panasonic is also working on building 4680 cells in the US, but their factories won't be ready for a year or two.
We know LG is also working on building 4680 cells, but their factories also aren't ready.
I really just don't understand what Tesla could have or should have done to somehow get more US-made battery supply.