Interesting. About my opinion on Prince Harry's, his situation living abroad seems to me has the intention of being financially independent, wanting to step aside from royal duties and mainly, his inability to tough it up with the tabloids like Kate and William did during the many years before the marriage.
I don't think there should be any accommodations around his needs in regards of the Counselors of State participation. I see him more of a loose cannon. He reacts into the tabloid trappings rather than stand his ground and ignore their noise and nonsense like Catherine did years ago when she was the tabloids' bullseye.
Princess Anne and Prince Edward seem to be the best candidates to lead this team in the absence of King Charles III and Prince William. The world is full of crazy people looking for fame that could repeat the
1908 Lisbon Regicide, so the Counselors of State situation needs to be in place soon and not after if the need arrives.
If Prince Harry was to be regent to assist Queen Catherine and an under-age king George, or as a member of the Counselors of State, his lack of control and loose lips with the press would rock a future King George's monarchy like if it was 1848. Plus, how do you make a person work in a country he doesn't want to live in, nor even for family gatherings, for being so busy with pushing his family brand in the USA?
If I was his employer, I'll tell him good luck on your career in California and
don't let the door hit you on the way out. Then proceed to the seriousness of the bigger picture for The Firm, organizing stability for a future King George.