Going by the consultation paper, sending a PM wouldn't be "public" so wouldn't be covered. Your second example would be covered. It's worded about as broadly as the NSL and probably just as difficult to enforce outside of HK.All I can say is get your donations in before they introduce the law
On the fringes this would be hard to police I would have thought. As an example if I sent you all a PM would that count? If I posted an appeal on FB not specifically aimed at HK and someone copied it on here would that count?
Will be interesting as Shri says.