Which is better for educating one's son: enrolling him in Al-Azhar or in language schools with a private Quran tutor, and will that affect his religiosity later on, given the desire to teach him Islamic sciences and practical qualifications?

The choice of study depends on the student's inclinations and academic level, the family's needs and financial circumstances, the educational environment, and the state of society. However, Islamic knowledge (Sharia sciences) is the best. If an opportunity arises to acquire it in a fruitful, systematic manner, with the father able to provide for living expenses, then it is the best. If that is not available, then let the son memorize the Quran and receive Islamic knowledge from trustworthy scholars while also enrolling in general education.