In trying to think of a way to get you to understand this try the following example
William freezes his sperm or takes Kate’s eggs and creates a frozen embryo. Then his entire family gets wiped out by a plague or car crash etc.
Now can Charles go create a new heir with Williams sperm. no.
If Kate is still alive but William and children are dead can she create a new heir with his sperm. No...could they do something hinky and secretly impregnate her with her claiming she was already pregnant..sure but..if nothing underhanded happens..
Harry is the new King when Charles dies
When Harry dies with no children born of the body..assuming that happened..can Archie be King.
Not if he was born from a surrogate.
Will all the rules change in the future..it’s possible. They changed the rule about the first born daughter being eligible to rule .but as it stands today..the law is the law.
Born of a surrogate means no King and no peerage
What makes you think Harry & MM faked her pregnancy and Archie was born from a surrogate?