Yes, Christ University accepts open board students for BBA admission. I completed my BBA hons from Christ University in the year 2020. I chose the Science stream in 10+2 but after a few months due to an unfortunate event, I had to drop out of the school. Then I completed 10+2 from open-board.
National Institute of Open Schooling (NIOS) is recognized by the Government of India and it is recognised all over India. It is equivalent to any state board. It is clearly mentioned in the eligibility criteria for BBA on Christ University’s official website that candidates must have passed 10+2 from a recognized board (Karnataka/ NIOS/ CBSE/ ICSE/ State Boards) in any stream.