If you cook at all a solution like Mealie becomes your cookbook. Its trivial to create grocery list for when you take the time to plan out your meals for the day, week, or month. If you are not shopping by yourself, everyone on the app can just pick up things in the grocery store independently. Its an actual time saver
Mealie exposes an API so you could theoretically expose it to another solution like Home Assistant and have your grocery list sync with your errands list. Suddenly you have the ability so that anyone using Home Assistant could get an alert when they are nearby the grocery store or Costco to pick up things on this combined list. Maybe your partner is walking by a store you've created a zone for, with items on your master list, gets an alert, and they can mark off some things that they picked up and it syncs back to where the items were originally added. Your inventory is then updated based on marked off items.
Now imagine if you did not have to come up with the bespoke master list for all the stores you go to and it can determine when to send that alert. You can also just snap a picture of your receipt or shopping cart and it is all figured out for you.
But you could just use piece of paper with the magnet on the fridge.
Theres a lot of manual process that can be eliminated for things people already find convenient enough to do manually. Local models can easily handle much of this already.