I wish you luck. Ostensibly you can export Blackboard courses and import them directly into Brightspace; effectively, you have to go through the imported course in Brightspace to check each element of each course and, in many cases, reset links and the like. I should think, also, you’ll be working on formatting after importing as well.

https://www.reddit.com/r/Professors/comments/14gdg8f/anyone_have_experience_with_d2l_brightspace/