Kinematic grenade bounce fake physics?

Is it possible to emulate the quake bouncing grenades without using real physics? Here’s the effect I’m going for:

I imagine I’ll be using Rigidbody.MovePosition to move the grenade, and use Vector3.Reflect to perform the bounce, but I’m having trouble getting the right vector to use with MovePosition. I have a gravity float and a speed float, I assume the speed float needs always reducing and the gravity will always be applied to the y axis, but am I doing this against vector3.Forward? I’m not quite sure exactly how to do this.

Use transform.forward for speed and vector3.down for gravity