Mobile Sales Quantity Entry App

I have an existing Google Sheets Order sheet and I want a lightweight Google Apps Script solution that opens comfortably on a phone so my salespeople can key in new orders while they are on the move. The form should appear in a clean mobile-friendly web app, capture three fields—quantity, customer name, and order date—and then append those values to the next empty row in the Order sheet. Aside from Google’s default type checking (number for quantity, date picker for the date), I don’t need any extra validation or duplicate checks.

You can build the UI with an Apps Script —whichever lets the phone experience feel native and fast. When you hand it over, I’ll need:
• the fully commented Apps Script files,
• a short read-me showing how to deploy it as a web app and connect it to my sheet, and
• a quick demo video or screenshots proving it works smoothly on a mobile browser.

That’s it—straightforward data entry, no bells and whistles, but it must be reliable and easy for my team to use daily on their phones.