ScraftyIsTheBest
On to new Horizons!
Generally, when there is no explicitly confirmed release date yet, listing worst case scenario ie projecting the tentative release date as late as possible is the smartest move in terms of keeping consumer trust because in the event that the product in question has to be delayed (which is extremely unlikely in the case of Pokemon anyway), it means consumers don't have the pre-conceived expectation to be seeing the product released sooner because of an earlier pre-expected "tentative" release date, thus making consumers less likely to be upset over a potential delay because they were originally promised an earlier release period.Anyway yeah there's no reason to take the eshop dates at face value. Why they're so far off (Even in terms of "Winter" going into 2024 that would likely place it around...March, I think, not April) who knows but those are always the worst case scenario. Engage's DLC punted everything to December 2023 and then turned around and released Wave 2 two weeks after the game came out.
So the eShop tends to make tentative release dates for things that don't have an explicitly confirmed date of release projected as far off as possible in that regard so that they make sure to keep consumers' expectations in check and prepare for any possibility of worst case scenario. It's smarter to list a tentative release date as worst case scenario so you don't risk promising consumers something that the developers didn't say and potentially upsetting them and shattering their trust.
Amazon itself also does this when delivering products: it's very common practice for Amazon to list expected date of arrival for a product you order as far off as possible so as to keep a consumer's expectations in check, and it is pretty common for things people buy from that site to arrive sooner than the date the website itself lists as the expected arrival date. Listing worst case scenario as the expected/tentative date prior to actual confirmation is considered the most smart way to handle things from a business standpoint, especially when it comes to keeping trust with consumers.
Most likely, the DLC will have Part 1 around September-November, while Part 2 will most likely be December so that Part 2 can push more DLC sales for the Christmas holiday for 2023.