considering how much mechs and tanks tend to move around, a lot more so than something like the bf2 tanks, which also popped smoke. there'd have to be considerations planned out for how the smoke/smokerounds behave if its gonna be useful or not game breaking somehow.
If we are talking personal smoke dispensers, then they have to be able to cover a retreat or in some cases, an advance. a puff of smoke centered on the mech might not cut it, due to movement rates putting it out of the cloud too quickly for it to be useful. I think that maybe then personal smoke dispensers might launch out smoke clouds about 90 meters out in a starfish pattern. That'd oobscure a 180 m diameter area, which would give any unit some ample concealment for a few seconds of advance or retreat no matter the direction of movement.
In regards to artillery smoke. The post nuke haze pretty much nails this. Have a localized post nuke haze that saps energy weapons of their power. The nice thing about this is that it can be used to cover a strategic advance through the no mans land areas of the maps, a retreat, or be used to screw over a large group of fire support or energy hogs and cause them to reposition or wait till dissipation. What i don't know is how to let whoever has that ammo in question, know what you want to do with it. Almost seems like something you'd need an RTS style commander interface to make use of, or some other strategic level of control. Maybe BA can place markers for offboard smoke strikes from an unseen artillery system, and simply not bother regular players with it? Maybe have offboard smoke strikes be part of the abilities of like a mobile HQ or something. i dunno
Firing smoke rounds as a weapon, like from a automatic nade launcher, only useful thing i can imagine out of it it to stitch a wall of smoke somewhere. Seems handy if you are BA at the time and need to visually mar someone's attempts to target you and you don't feel like using a flamer. Otherwise i think most people would opt for something deadly.
For the first two, i definitely think it should give temporary AECM coverage for a very short while when the smoke cloud is still active. Cause at longer ranges people are probably just gonna aim for your target bracket's center