perhaps just get the control inputs of your Pawn, then feed them as steering inputs to your projectile… this way you’d be able to control both actors simultaneously
Just launch the projectile using your desired velocity, don’t set it to homing …
In your projectile’s event graph, Get Player Pawn or Get Player Controller, get the control input values (maybe pitch and yaw, I guess you are using mouse control), use these inputs in your projectile BP (multiplied by a scalar) to add to world rotation, you might need to smooth the inputs using an interp node.