It’s not clear to me if you can visit other places, given that you submit a form asking for permission to go and stay in one place. There are checks at the entrance to all of the beach towns, we went to Mar de las Pampas, and while we weren’t checked, it was clear that cars with younger people were being stopped (I fit the baexpats demographic of grey or no hair so I definitely don’t look like need to be checked).
Pinamar is getting extremely bad press at the moment, due to beach parties, fights, and the resulting COVID outbreaks.
I’d plan to go, relax on the beach, not mingle with anyone, self-cater as much as possible. It worked for us.