Aside from it being a very unique grot idea. Why don't we have small 1 man tanks ? They could be like a tiny squadron wall to guarantee advanves in crowded territory.
I knew about the "Garden of Nurgle" but i just realised that Death guard actually has a lot of gardening tools and gears for acriculture. Like scythes, harvesters and tillers. Aside from scythes being a sign of "the death" too.
There have been mentions of larger Canoptek constructs, up to Battleship size even and the seraptek is already a big boy. With a little adjustment, would the brass scorpion read as a Canoptek scorpion ? The trim of course being still very chaos reminescent and the chainsaws might look more primitive
Why do wolves use helfrost weapons ? Sure, they do know a lot about cold temperatures and know their way of fighting around such terrain but on their own planet these guns wouldn't be useful at all right ? If they train on fenris, the fauna they encounter couldn't care less about getting frozen.
What are some guard models you want Iron warriors to have ? And the more important question, why don't you just ask your opponent if you can use them ?