For the cost of a ballistic missile submarine, which could be detected by Indian ASW (probably with the support of others), those resources could be poured into mountain missile bases (with thousands of portals for shoot and scout tactics). India doesn’t have the ISR capability to detect all of Pakistani missile bases, and wouldn’t be able to gain air superiority, not if the PAF has anything to say about it.
Pakistan should be studying what worked with Iran and where their vulnerabilities were.
Besides Pakistan also needs at least dozens of underground (under mountain) command centers for its military.