Some people prefer metal halide for veg because of the bluer spectrum of light. But the output of actual photons is less then HPS.
HPS has more red leaning spectrum which some people prefer for flowering.
But the plant really wants a high number of photons. Kind of like quantity over quality. But not really.
The quality is good for both so it's really just quantity of photons.
I know that's a really basic view point.
You can really dive deep in the light issue
But yes HPS is fine for veg. You might get a little extra stretch