Congrats to Alexey Kozin who recently added ArduPilot support for the F4BY board using ChibiOS. As far as I know, Alexey is the first to complete a ChibiOS port not including Tridge and Sid so well done! OneShot125 and Oneshot250 already work and D-shot is also on the way!
Specs of this new board and where you can purchase one are on our F4BY wiki here.
Congrats again to Alexey Kozin!