This is a website that contains resources and information to help prepare for the NBT. It's basically an online guide / a redirector to other websites and resources. There are PDFs, Youtube videos, links to unaffiliated websites and courses both free and paid.
Website: https://azaambie.github.io/NBT-Prep-Resources/
WARNING: THIS WEBSITE IS NOT AFFILIATED WITH THE NBT PROJECT. THIS IS JUST AN ONLINE "GUIDE" / "REDIRECTOR" FOR RESOURCES TO ASSIST YOU WITH PREPARATION FOR THE NBTS.