A:AnswerI play it on a Switch Lite, it works fine. The only problems are a potential lack of peripheral support, as the Switch Lite only has a USB C port available, and a lack of Joy-Cons. The first can be worked around using adapters, but playing this game using only the Switch Lite's buttons and touch screen is fine if a purchased drum doesn't work. The second problem is more major. One mode of the game is meant to be played with the motion controls of Joy-Con controllers, which are not included with a Switch Lite system. You would have to purchase a pair of Joy-Cons, and have some way to hold the Switch Lite in tabletop mode, in order to play that mode.
A:AnswerIt likely got delayed, but I don't really know why considering they literally have to print copies. I did see that they're including a pin set in the box as well, which is probably an apology for the delay.