A:AnswerSeems to be only available for store pick up. Same thing was happening to me - getting a sold out message when trying to checkout. Keep trying and my persistence paid off.
A:AnswerYeah it's because they are currently sold out. There also isn't an exact restock date yet. Some people do say it might not be it will be restocked until around May or June. That is just speculation though, nothing confirmed.
A:AnswerEverything I’ve read has said that there is a restock coming but Nintendo did not tell when, that could potentially take up to a month I would assume. Their manufacturing got pretty delayed and even though they are starting to manufacture again it’s not at 100% manpower still. If you keep checking in the mornings I find that there are more restock opportunities and I was able to snag one at about 10 o’clock in the morning one day.