Is it forbidden to meditate on God's creation for a worldly purpose, or in order to distance oneself from disbelief, from five to six in the morning, at sunrise?

Contemplation of the dominion of the heavens and the earth is a great act of worship. Meditation on the creation of the self to relieve stress is permissible. Combining both intentions is fine. Your mentioned action is good and there is no harm in it. It is not forbidden to worship Allah after the Fajr prayer until sunrise; rather, it is a time of remembrance and worship that the devout seize, and it is a time when provisions descend and blessings alight.