Modern diesel/AIP subs can be quieter than nuclear subs in certain situations, especially when running on batteries. But saying nuclear subs only have a range advantage isn’t really true. Nuclear subs can stay underwater for months, move much faster, cover huge areas quickly, and stay on patrol much longer without needing to surface.
Also cruise missiles and ballistic missiles aren’t the same thing. A cruise missile submarine usually has to get much closer to the coast to launch, while ballistic missile submarines can stay much farther away and still strike targets. Hangor will definitely be a big upgrade for Pakistan, but India’s nuclear subs are built for a different role and bring different advantages. Next upgrade should focus on getting longer range for those cruise missiles, and after that focus on developing ballistic missile submarines. China has all we need for tech transfer but it will be really costly and take a lot of time.