Agreed.
But this a complex problem.
First, we need the ability to scan food quickly, and know what it is. The Swiss have https://www.openfood.ch which is awesome, but that is just the Swiss. Alternatively, we could use our bonus card of the grocery store, or use OCR on the receipt. This'd give us the names of the ingredients at the very least.
Next, at a minimum, we need a way to detect and read the expiration date, allow to sort on this, and have some red/yellow/green markers for warning. On food, there is no standard for this as of yet. We'd need standards for perishable food like bananas and tomatoes. How long do those last? Perhaps ML/AI would be of help here.
I'd also argue we need food allergy warnings, but that'd be a feature for after 1.0 (just add a temporary warning).
We also need to store these ingredients in a database which is accessibly to the customers. I know some are thinking SaaS, cloud, etc but I prefer privacy TYVM. We need to be able to modify this database, and use say cron jobs for the expire date.
Next, we need the ability to connect this personal data -while containing privacy- with recipe databases (for which there is no open standard, and is pested with copyright), which would be used to match the ingredients which A) user has, and are to expire B) user prefers to use C) user doesn't mind buying. The suggestions to the user are based on ML/AI, but the user can set a day they want to 'experiment'; then a cuisine is selected the user normally does not follow (this last feature not for 1.0).
A later feature would give accurate feedback to the user how long the cooking is going to take based on ML/AI.
Finally, a backend with grocery store DBs is used, to order new ingredients/foods. This has support for price, brands, S&H, food allergies, shop opening time. Backorder support, suggestion support (together w/recipe backend).
(I ignored drones delivering the orders.)
Ambitious perhaps. Does any of this exist?