Flying with spear reminds me of the flying sword Hildibrand uses :3, could be a super MGP reward !

On the idea of a dragoon specific mount, I thought the jumping thing could be quite cool (although a toggle passive, imo, would be far more... roleplay-y like, or at least instant mount outside of combat). To avoid pathing problems simply have it require flying to remove pathing, if you land on something unpathable (can't 'stand' on it) then you just sort of sun Wukong stand on your spear (impaled into the ground or whatever). In this way it doesn't disrupt the game when you've not unlocked flying yet.

For flight, still thinking dragoon, getting like 7 wings to pop out of your back with Hraesvelgr or Nidhogg theme'd wings would be neat, gives a very Legend of Dragoon vibe.