I see nothing significant about them, they’re just achievements. Of course, I just activated my account and am only a Bronze member, so there could be something else that I dont know.
They are still in beta as such, it has to be determined how hard/easy it is to gather them before it can be equated to rewards.
This was a topic started some time ago related to this, https://forum.avast.com/index.php?topic=160021.0.