Khan Academy has announced its plans to offer more AP support to teachers, as well as students.
See https://www.collegeboard.org/membership/all-access/academic/ap-announces-expanded-student-teacher-supports-and-khan-practice-2019
The new supports will provide students with meaningful feedback that will increase their understanding of course content throughout the year. Among them is the AP Question Bank, the most commonly requested resource of the AP teacher community. The Question Bank is a library of real AP Exam questions—sortable by topic and skills—that teachers can use to create practice tests and assignments for students to help identify and address potential learning gaps.