There are just so many inspiring people who have lead remarkable lives of service, some of whom are public figures, many of whom we have never heard of. I think this would be a ceremonial and diplomatic role, but it could also be a way of shining a light on an aspect of UK life, culture, scientific, sporting, or arts achievement. How much more inspiring for young people to have a David Attenborough, a (albeit no longer possible) Neville Marriner, or any of the many scientists, computer engineers, civil servants, a retired Marcus Rashford in the tradition of Sebastian Coe, Professor Ngaire Woods, Professor Susan Springman, who I had never heard of until her recent election to be the head of an Oxford college, Prof Dame Donna Kinnear. You don't reach the top of a profession in that way without some appreciation of service, dignity and diplomacy. I do wish people could open their eyes to how positive this change would be. A message that achievement and service lead to high positions, not birth.
Some might be more to your individual taste than others, some might be more circumspect, others more charismatic/loose cannons. But the tenure would be short.
I suppose one problem is that all the dubious responsibility of taking the public eye off dubious government policies would fall on the shoulders of vulnerable Love Island etc contestants and their antics.