It's not often that we see a Switch game hit retail without the eShop version already being available, but that's the case with Cooking Mama: Cookstar. We have confirmation from the PR team that Cooking Mama: Cookstar's physical release is indeed available now, and you should be able to grab it from a number of online retailers.
If you're looking to snag the eShop version, you'll have to wait a bit. We did get confirmation that the eShop release "should be coming soon," but a specific date was not shared. Hopefully we get a more clear-cut answer on the eShop side of things in the near future.