Patching/refreshing the pointing between stone setts

We’ve got an area of back yard that is done in old stone setts. This kind of stuff, but squarer (this is not ours, just an example picture from the internet)

The pointing is a bit patchy, in places it’s good and solid, in others it’s a bit flakey, in others it’s sandy and powdery, in others it’s basically none existent. There’s also a fair amount of moss in the flakey/non-existent bits. What’s the best/easiest way to approach tidying it up? Our thoughts are currently to jetwash it all to blast out the moss/soil/sand/loose bits and then use some kind of brush in stuff that will hopefully match-ish the bits that are solid (which look like cement if I’m honest).

Ideas?

The brush in stuff seems to only last a couple of years IME. I’d go for the sharp/soft sand mortar and Test Cricket approach. If you have a gazebo you might not even need to miss a nice riding day.