Wouldn’t really take much to convert the existing ones. Set of tin hats and one of respirator bags. Only thing missing would be a Lewis gunner and you could possibly just nick one of those from your late interwar range.
Currently a bit of gap in the market. Renegade are OOP and unless you are in the US, the shipping costs kill any order from Brigade Games stone dead. I suspect Wargames Atlantic will produce some in plastic at some point but they won’t be as nice as Paul’s sculpts.