I'd second (third, by this point, I think?)
Ship/Weapon Pack.
I'd also suggest:
Seeker - Though, okay, it
does also add some things that are... well, hm. I was going to say 'not really vanilla style', but, uh, given the existence of the super-redacted ships, they're not actually that far out of it, are they?
Tahlan Shipworks - This one does add a some faction-lite stuff - the 'great houses' equipment - but it's all stuff the independents can get, not an actual new faction per se.
Underworld - The mod includes a new faction of more-pirate-y pirates in the form of the 'Starlight Cabal', but it looks like it's got a config option to turn them off, at which point it's just a pack full of vanilla-thematic pirate ships.