I agree with everything you said but it is important to note that it is NOT automatic as the poster stated.
Parliament may deem at the time they don’t want Catherine as Regent and would rather have someone that is in line for the throne. If Not Harry or the next in line Andrew then it would be one of Andrew’s children and so on.
Imagine a scenario where Prince William became King as a Minor. Would Parliament let Diana be Regent??? Doubt it.
Catherine isn’t hated by the people of the UK. Harry is. The Markle fans are some of the scariest people on the internet. They’re desperate for William and his kids to die so Meghan can become queen.
King Charles amended the members of the Counselors of State. Harry can’t be removed but Charles fixed it so he can never be called upon to represent the King in case he is ill.
The best chance Harry has for a crown is to work at Burger King.