One thing obviously missing from the Ambri website is a "datasheet". You know, the one-page summary of the product's characteristics that they are trying to sell to you? No sign of one.
I suppose it won't be, if they aren't prepared yet to sell a product to "just anyone", but it's also a sign that they haven't prepared to sell any products at all. Not yet at least. The photos you see may be still experimental units.
Another missing thing, a little more subtle, is any claim about testing, except "we have tested it". What I would look for are tests done by independent bodies that would evaluate the performance with a suite of calibrated equipment, climate controlled building, and so on. The test would publish data on the lifecycle of these cells, similar to the tests done on lithium cells, demonstrating round-trip efficiency, variables such as temperature and rate of discharge. Connecting back to the first missing item, if there are experimental units being built, well then for whom? Surely that kind of test would attract attention. And be worth touting on their website. Not a word of what all these containers' worth of cells are going to be used for.
Third thing that's missing, though it is much less likely to be on the public website, is contact with the US military because this thing is clearly targeted at needs such as theirs. Which suggests an answer to what's missing at question 2 above!