Everything will work as long as the form is already loaded into the browser. The only thing you can’t do is submit the data. You will need a data or WiFi signal for that.
So, you could fill out the form in the absence of any internet, and send it on when you are back within range.
I have designed the app to refresh to a clear form immediately after submission. This means that as long as you do not close it, you will always have a form ready.