this has been discussed before and darkflow slightly implement it, but ill prob say again.
Head: increased damage, probably kills in game anyway
arms: either one arm loses control or smth or it could just shake and the gun shakes a bit
chest: increased damage, slightly less damage then in the head, heavy breathing, and maybe a slow death that can be solved via medpack, also shaking
legs: if too much you start to limp
waist area: limp ig, but blood loss slow death just like chest but slower
I will take the liberty of sharing my suggestion.
also uhhh edit, maybe add more voicelines like slight screaming and stuff like that
that is perfect too, maybe implement all of the suggestions or smth
Im not sure if the fast paced gameplay can accommodate these.
Fallout has similar mechanics I really enjoy them, but honestly if a soldier gets seriously hit, the player will just continue with another one.
It would be pretty pointless to add those debuffs since i would just switch to another bot to save time and have a fully functioning soldier.
That’s something that often wouldn’t be possible. It’s quite common for your whole squad to die before you do.
Plus it could also affect gameplay in some ways. For example, you’d be forced to change into a soldier who potentially has a different class and a different weapon than you’d need at the current moment.
Presenting it as if the change would have no significance is deliberately disingenuous.
This isn’t escape from tarkov or dayz type of shit 
Then you only need one treatment needle to solve all problems
From a practical perspective
this is bad
As long as the enemy effectively uses strafing and explosives, all your soldiers can become disabled
So how should players treat disabled characters?
Suicide? Leave it alone?
They don’t even need to kill you directly to win better
I’m here to fight
Not here to play the role of a disabled person or a disabled person making machine.
Disabled person simulator 
Like EFT?