As of now, firejet in the AvatarState is toggle-able. That is canon, but they way the toggle works isn't exactly canon. Here is my suggestion:
When you are in firejet in the avatarstate, instead of working like the real firejet, it should be like how a spout works, using the wasd keys to move. The particles would be the flame particles coming from the players feet as they fly. How this would work:
Mobility:
When you press your running key while in firejet, it will make you go faster like regular firejet does, and then 2x fly speed when not pressing the key.
Attack:
While on firejet, you could use moves like earthblast, fireblast, watermanipulation, airblast, airswipe, earthsmash, fireburst, icespike. These are the moves that require the least amount of concentration (imo). This is completely canon because most of us have seen the part where korra bent almost half a mountain while just using her feet to stay in the air.
When you are in firejet in the avatarstate, instead of working like the real firejet, it should be like how a spout works, using the wasd keys to move. The particles would be the flame particles coming from the players feet as they fly. How this would work:
Mobility:
When you press your running key while in firejet, it will make you go faster like regular firejet does, and then 2x fly speed when not pressing the key.
Attack:
While on firejet, you could use moves like earthblast, fireblast, watermanipulation, airblast, airswipe, earthsmash, fireburst, icespike. These are the moves that require the least amount of concentration (imo). This is completely canon because most of us have seen the part where korra bent almost half a mountain while just using her feet to stay in the air.