Regarding the ACT, you probably need to talk to the Admissions office. Pitt uses a rolling admissions process, so you’ll want to understand how future tests will be considered when an applicant submits their app.
I believe that Pitt does their own GPA weighting. The common data set reports on a 4.0 scale (unweighted), so it’s impossible to tell from it what their weighted GPAs would be by Pitt’s calculation. The reality is that Pitt is a well-regarded university, so I would say it’s safe to assume that many (if not most) students have taken a significant number of honors, AP, IB, and/or DE courses.
I did see a freshman class profile for 2017 that indicated 95% of the enrolled students took at least 1 AP class, and that the school of nursing had 153 students enrolled (https://oafa.pitt.edu/explore/class-profile/).
Overall, I’d say that the Pittsburgh campus is probably a reach, and that your son will definitely want to consider some safety schools.