My main reason for using an app for Walgreens anyway is so I don't have to log in each time. When I go to refill my prescriptions, I'm usually in a hurry and just want to do it and move on. Refill usually takes maybe 4-5 clicks? And often less than 2-3 minutes.
Whereas on the website, between logging in and finding the medications, it's a much more involved process and I often need to use a computer to navigate it.
Oddly enough the CVS mobile website is pretty streamlined so I often don't need the app for it. And their mobile site supports passkeys whereas Walgreens doesn't.
I know, meme and all. But MVC and API based are two separate things, and fairly easy to support both in most frameworks. You can use built in view while exposing the data itself.
Kind of what it says on the tin: it's the UI view of your application. Usually some kind of HTML is populated with data using a template language like C#, Python, etc.
The only reason it's "backend" in this instance is that instead of sending the HTML and template for the end user to fetch the data for themselves (eg. via an API) it's pre-filled on the server before being sent as a completed blob of HTML and data.