Is pursuing a master's degree in Islamic banking, even though its worldly gains may be less, pleasing to Allah Almighty by harnessing knowledge to serve the religion?

If what is right aligns with a person's inclination, then they have been guided to immense good. Your specialization in Islamic finance and financial science governed by Sharia principles is a righteous deed, so do not let a lower financial return be an obstacle. The truth is worth sacrificing for, and whoever gives up something for the sake of Allah, Allah will compensate them with something better.