Based on the very clever and yet simple idea posted by @Wohler, I added some functionality to their setup. If you have a Pro membership, you can even add recipes to your shopping list!

It's based on one regular list and two smart lists.
The regular list is the Shopping list, where everything you might want to buy at some point is added. After you add items, mark them as complete.
Typical items:
[Dairy] Milk
[Fruit] Bananas
The [text in square brackets] makes it easier later, see below.
If you want, you can add (static) information about the number of units/weight etc.
To add the items you want to buy, just incomplete them.

This list also includes all your recipes (for Pro members):
Example:
Spaghetti with meat sauce tag:recipe
Ingredients are listed as sub-tasks, example:
- [Meat & deli] Ground beef (400 g)
- [Pasta & rice] Spaghetti (300 g)
- [Vegetables] Onions (2)
The sub-tasks should not be tagged with recipe!

The two smart lists are:
Recipes (search: list:"Shopping list" AND tag:recipe) - here you decide the menu, just chose which meals you want to cook.
By incompleting meals, all their ingredients are added to the next smart list:
To buy (search: list:"Shopping list" NOT tag:recipe) - shows all items you need to buy, either from recipes or from items you've chosen from the shopping list. The list is easy to use if you sort by task name. The reason for the NOT tag:recipe part of the search is to show the ingredients (sub-tasks), not the meal (task).

Just complete tasks until you're done.

It's probably easier to add all the items to your shopping list on a computer, including all relevant recipes. To decide what to buy, this can easily be done on a mobile device.

Good luck!