The 300 km rang is for export only to comply with intermediate range convention. The domestic variant has much larger range. It can make an evasive move from enemy anti ballistic missile. As well it can make curve trajectory or C trajectory to confuse enemy AD battery . I think this is fearsome weapon because it is cheap! and self contain as well as variety of munition headWS600L is not a HGV system. It is just a very fast, very long range rocket like an MLRS system on steroids.
It seems to be a development from those pseudo ballistic missile, long range rockets. It just so happens to break through hypersonic speeds because it has a pseudo ballistic trajectory although the video seems to suggest it is guided and maneuverable. It is sort of a very inexpensive, low tier DF-ZF weapon for <300km targets and something a bit above the long range MLRS used by China that can hit targets within 1m accuracy from >200km away.
But is this in service with PLA?
very suitable for Taiwan contingency. It has the range the sophistication and can be produced in large number