How long does a freewheel cog last?
3000km is enough of a wear life for a singlespeed freewheel that I would say there's nothing necessarily wrong here.

One way to check wear is just looking at the side of the freewheel teeth that contacts the chain versus the side that doesn't. The more asymmetry, the more wear.

If you ride it like it is, it probably will break in and get quieter, but what's happening there is your chain's pitch elongating to "catch up" to the freewheel, which isn't necessarily a good thing.

I don't have experience with the Halo one but it sounds like it might be a little too boutiquey for its own good. The cheaper Shimano freewheels are pretty excellent at reliability, wear life, and not being too painful to replace when they do wear out.