Tehy dont have any royal patronages any more. They retained some charities but they are not doing them as representatives of the queen. but its possible that yes they will be persauded to give up their UK charities in 2021....
Yes but only people like us who discuss this day in day out really know or care about the difference. Especially as they use their titles when Zooming them and presumably would when Instagram shows them "just popping in" to visit Luminary Bakery etc. And it gets much more murky because Meghan still is still officially patron of the National Theatre - a patronage she was given the the Queen, not to mention the Commonwealth stuff. Most people wouldn't realise the difference between "royal patronage" and "private patronage" in this context.
So if they do come over next summer they'll be able to do things like this and possibly Trooping to top up their royal credibility and fairy dust to show that they aren't just ordinary celebrities trying to sell you something, before heading back to the US to talk about how glad they're out of the toxic institution that is the monarchy and their nasty relatives again as well as back to topics they shouldn't really be talking about whilst using their titles. And Omid Scobie will be able to write another book about their experiences. Talking out of both sides of their mouths seems to be part of their business plan.