Welcome to the forum.
Once you have your list you would display it in a repeating table with the state and a check box.
Will you allow more than one state choice at a time? A drop down would probably be simpler for the user in that case.
If only one then you put a rule on the check box that loads the state name with the filter selected = true into anoth field in your form.
Then base your conditional formatting on your additioanl section to appear when it is not blank and you can display the selected state.
You could put this into a repeatin group to allow multiple states to be selected sequentially.
If you want the user to select a group of states then you could still use the filter but you are going to return more than one result or just get the first selection if in a non-repeating field.
Alot of how you set it up depends on the form flow.