Didn't the Queen strip these two of their royal titles?
No. Just the "HRH", and the right to use the word "Royal" in whatever fake charity stuff they were trying to market early on.
Harry is still Baron of Graymatter.
A duchess is not a royal title. Dukes, Marquesses, Earls, Viscounts, and Barons are members of the Peerage, and are not royal titles. Although members of the royal family will have peerage titles. For example, Prince William, Harry’s older (and more sensible) brother is “His Royal Highness”, but also Duke of Cambridge. Harry and Meghan are Duke and Duchess of Sussex, but that is not a royal title. “H.R.H. Prince Harry” would be a Royal title.