Tandoor caches your most recent recipes so that’s available when offline, I don’t use the shopping list feature so I can’t say for sure if it works the same way but I imagine it does

This is a great web app that’s easy to setup using docker and I’ve been using for a few years now. The developer is responsive and has done really good work getting it mobile friendly for the meal planner. The recipe importer works well and I highly recommend it!