I want to start an app based business, which is similar to delivery app. Can I build a complex app like delivery app?
Yes, it doesn’t sound complex.
Maybe you could describe your “delivery app” a bit more… To get a picture of your need from 2 sentences is a bit difficult.
Basically you can do lots of things with AppSheet like sending emails/SMS, create documents, do calculations, approval processes, show data on dashboards and many more use cases.