It is confirmed due to I am trying it out indoors. Once I put the drone outside, both EKF and is_armable become true.
GPS: GPSInfo:fix=3,num_sat=9
Gimbal status: Gimbal: pitch=None, roll=None, yaw=None
Battery: Battery:voltage=15.732,current=0.61,level=97
EKF OK?: True
Last Heartbeat: 0.901965425
Is Armable?: True
Mode: ALT_HOLD
Armed: False
I also provide my feedback on dronekit 2.9.2 over here.