Application developed for measuring gardens using gps or other digital means N

I’m looking to development a web based app (not iOS or android) that can be sent to clients for them to be able to measure their own garden lawns using gps (or any other effective method), to measure and calculate perimeter and area of lawn areas in gardens . This needs to be done using their cellphone . Theire is currently a similarly one on the App Store. Pictures attached.

We are an artificial grass company. It’s mainly an link that gets forwarded to our clients where they can open and measure their own gardens. We will then be able to do our quotations from that. I don’t want an app that needs to be downloaded.