Can the knowledge mentioned in the verse "And said he who had knowledge from the Scripture, 'I will bring it to you before your glance returns to you'" be attained by humans through scientific advancement, or is it a divine knowledge خاص بالله and bestowed only upon whomever He wills?

Most exegetes believe that the one who had knowledge from the Book was Asif ibn Barkhiya, the companion of Solomon (peace be upon him), and his knowledge was the Greatest Name of Allah. They differed in identifying this Name, and the more accurate view is that it was concealed for a wisdom. This knowledge is not material; rather, it is from the Book, and it is a karamah (a miraculous favor) granted to a saint who is not a prophet. As for the knowledge of Al-Khidr (peace be upon him), mentioned in the story of Moses, it is knowledge of the unseen received through revelation, and Al-Khidr is a prophet to whom revelation was sent. Knowledge of the unseen cannot be attained after the cessation of revelation. Therefore, the summary is that Asif's knowledge is a karamah that some righteous individuals can attain by supplicating with the Names and Attributes of Allah, whereas Al-Khidr's knowledge is a revelation that ceased with the passing of the Prophet Muhammad (peace be upon him).