I've always been of the opinion that shipbuilding in Discovery, at least for the Houses is similar, though maybe faster and more efficient than Military shipbuilding now.
i.e. instead of having people building the hulls they're being built by large industrial machines with people contributing to installation of components and such.
I still hold that say Battleships and Carriers at least take close to a year to build in Discovery, but smaller capital ships like Cruisers Destroyers and Gunboats are being mass produced and churned out several at a time every couple months.
And even though in my mind a Carrier takes close to a year, they're not building them one at a time. So say, every year they roll a bunch of new carriers out of the shipyards.
At least in the Houses.
As for pirate factions (Other than Outcasts and Corsairs, who have their own de facto Houses), I'm still not sure how they'd ever have the industrial capability to compete with House military ship production.