I'd love to see a whole lot more available movement while prone. Like being able to look and shoot in any direction without moving the whole body.
I'm not really sure how you really lean while prone. I'd rather see the lean keys be used for rolling while prone.
The only thing I don't like about prone is that when you turn around, its as if your character has an axle in the ground about where his stomach is and he just kind of rotates around it. It looks dumb and exposes your legs too much and in an unrealistic way.
Being able to roll onto your back would be a great feature, even the way they have it in siege where your character switches their legs forward would be better than what we have now.
I like the idea of make Q and E during prone make you lie on your side so that you can aim to your sides. So pressing Q would roll you onto your left side, allowing you to aim right and vice versa for E.
Something like the R6 Siege or GR Wildlands system would be great, where you can spin around without spinning the whole body. This would also accomplish the "lay on sides" positioning as wall, as that's what would happen if you looked 90-degrees off to either side while prone.
I agree that turning on your back when prone and Q/E laying on side is a healthy prone mechanic/feature in a military FPS game... Although, I'm not sure if it's a good idea for this specific game. The ability to turn around and lye on your back when prone is more of a quality of life thing compared to the Q/E prone as that posses very strong alterations on game-play.