I understand that it is normal to create an empty object and then fill it out, but if the user leaves the page before the form is finished, it creates a partially complete object. Is there a way to take the information from the fields and add it to a new object when they hit a submit button?
Regarding the forms and user input, page closing, submit etc, I have following to share with you. Hope it will help to construct your applciation logic.
If the user leaves the form unfinished, then do you need to save that object? I think in a normal scenario, we only save those object which user wants to save or user wants to create (in that case he will not exit the page before completing the form). If user exits, that object hasn’t been committed yet so no worries. That partially filled object you are referring to will not interfere in your application.
Also there is a page close action for forms (modal popups), in which you can call a microflow to be called when a page is closed. In that close action, you can use that in memory object for whatever you want to do with it
If user hits submit button, you can customize the behavior of saving/submit in a microflow
If you want to add validations so that user don’t skip input fields in the form, you can make the fields required and also a number of other validations are available
Still if you only want to copy details from one object to a new object at submit button, you can do that in the microflow set as the save/submit action