>I do have a suggestion for your app though: Have it compare your basket of goods across different markets in your region to show you the cheapest option.
I'd settle for just being able to sort items by unit price... I'm sure this is a [regulation-]solved problem in Germany though
Sorry, yes, I'm not German and haven't used it. It was an idle complaint about how trying to use grocery store (or other similar) sites is difficult because they prevent you from being able to sort properly, for example by unit price. Sometimes they change the displayed unit per product so you also have to convert them to compare manually (less of a problem for metric, but like, drink brand 1 €2/100ml, drink brand 2 €13/1L etc).
As I was writing it, I realized that this kind of tactic just feels like it would be banned in Germany
Stores are required by law to provide the price per unit/weight/volume alongside the price, so you can directly compare the price of a pint of beer to the 0.33 liter bottle without calculating anything.
I just checked and REWE only lets you sort by absolute price. But honestly, you can compare prices so much better on their website than in a physical supermarket already [0].
I'd settle for just being able to sort items by unit price... I'm sure this is a [regulation-]solved problem in Germany though