after a lot of testing, almost all shotguns i found to be a lot viable, while a few ones seems soo trash, its almost like ubisoft forgot about them:

kapkan shotgun, frost shotgun: poor damage and a lot of spread, while some shotguns like the lesion one have an very low spread with 45 damage, these ones spread a lot and does 22-26 damage

lion/twitch/grim/doc/rook shotgun: extreme poor range, spread, damage, everthing on this shotgun sucks soo hard, you gotta be almost melee to kill while shotguns like supernova you can kill from a lot further without ever aiming

thermite shotgun is almost fine, but need an recoil reduction to make it actually viable, still fun to use.

conclusion: most shotguns seems to be in a good place now, but these ones are very bad compared to any other, i suggest buffing kapkan shotgun with a better damage, thermite with better recoil, and lion/grim etc with a better range and spray