As a really specific example in the case of Apple, I really hope the DMA causes wider availability of browser choice on iOS so that we as a business that ships a web app can offer our customers features like notifications and other PWA benefits. Our customers are somewhat willing to switch browsers to get the best experience when using our app. But switching to Android? Not a reasonable ask from us.
Most consumers also have jobs right? Making their lives better and easier at work, increasing competition to give their employers more opportunity to thrive, is just as important as making their groceries cheaper.