Darkness rises... and light to meet it.
Why it is hard sci-fi
Soft. The film adds one notable engineering moment, the Holdo manoeuvre, a hyperspace ramming attack that is its only piece of working physics in the saga. The implication that any large mass can be weaponised by hyperdrive-jumping into a target is a problem that the rest of the saga has had to retcon. The films other working idea is the resource-and-fuel attrition of the Resistance fleet, which is presented as a real budget rather than a setpiece.
Science inside it
Hyperspace ramming as a high-impact kinetic weapon, fleet-fuel logistics under sustained pursuit, and a casino economy on Canto Bight that runs on arms trading. The Holdo manoeuvre is the films one moment of explicit engineering and the saga has been arguing about the implications since it aired.