Long live the fighters.
Why it is hard sci-fi
Villeneuves second part. The film extends the worldbuilding of Part One with the Fremen worm-riding training arc, the Bene Gesserit prophecy substrate as a deliberate eugenics program, and a sustained sequence of insurgent operations against an entrenched occupier. The science of Arrakis is the same as before and is now operationalised. Worms ridden, harvesters destroyed, and a crystalline knife economy under a religious framing.
Science inside it
Sandworm physiology, the Maker hooks as a working tool for opening segments of armour, the Water of Life as a physiologically active prespice that triggers Bene Gesserit memory awakening, and the chemistry of melange as a tetraploid-active compound. The Bene Gesserit Missionaria Protectiva is the films explicit social-engineering layer.