A cafe has a manual food and drinks ordering (verbally at the cashier) and cash payment process.

The orders are handwritten on a notepad, and verbally conveyed to the kitchen cook to prepare the orders.

The cafe does not use any electronic systems, but manually keying in total sales details into Excel spreadsheet on a personal laptop at the end of each day.

I want to recommend a QR ordering system and QR payment mode to the cafe.

1) What would the As-Is Model and To-Be Model look like for this cafe?

2) Are there any assumptions, business rules, issues and constraints for this type of scenario?