I think it's hard to get an accurate read on general public opinion on this issue as Megxit was essentially falsely politicised when it happened (Team H&M - liberal, left-leaning, #bekind crew; Team RF - socially and morally more traditionalist) and so anyone who responds to the polls probably has a heavy existing bias and links their stance with other political convictions they may have.
I honestly suspect that the average person on the street hasn't paid much attention to H&M's antics over the past 5 years and if asked, would probably say something like "Harry? Oh yeah. Seemed like a decent bloke, don't think his wife's been very good for him though, shame he fell out with his brother, that's sad that is. Would be nice if they could reconcile one day I suppose". So the resistance wouldn't be as hugely strong as it is on these threads, say, where we're all a lot more interested.
No big mea culpa set piece interviews or anything, just seep him slowly back in at the edges.
If it were me, I'd also tell him NOT to do any sitdown interviews about his family for at least a year!
Also important to remember that Harry is rapidly fading into the rearview mirror of the RF generational change. William, Kate and their children are seen as the current and future stars. Harry will soon be just another greying uncle with a dodgy past. So I honestly don't think a gentle detente will seem as jarring and new and dramatic to the gen pop as it does to us on this thread.
He'll just be another balding middle aged bloke with a paunch on the very edge of the family photos on the balcony.