I am pretty sure you are wrong.
https://commonslibrary.parliament.uk/research-briefings/cbp-9374/
The Regent is the heir to the Throne unless they have not reached the age of 18. In such a case, the Regent is the next in the line of succession who has reached the age of 21.
“Unless they are not domiciled in some part of the United Kimgdom…”
Harry would be DQ.