Something cool and game-changing that could be added to the game is the ability to have stims of different sorts. Kind of like the current Morphine, Adrenaline and Vaccine syringes in 3.0. Except these stims would give pros and cons. For example, adrenaline stim injection would cause you to be able to move faster with heavy weight, and buff the recoil control a bit plus buffing small things like ADS, reload etc. The cons would be when the effect is over, the user will experience fatigue (example). This suggestion was mega ultra inspired by Escape From Tarkov’s Stim “system”.
In addition to this, I think it’d be cool if in a place like Scorpion-7 and military bases, etc there were devices on the wall that would require power, and would give you a stim effect when you interact with it, and it would need a cooldown before you used it again.