Buyer here, when something doesn't sell It's probably one or a combination of the followings:
1- Your products are not attractive ( better alternatives, not good enough, not modular, etc..).
2- Your products are overprice or are too expensive for average buyer.
3- Your products don't get exposed enough (wrong category, good name, bad thumbnails).
4- Your products don't have the format a potential buyer wants.
5- Your products have few demand.
6- Buyer doesn't understand what the product is or what is it for.
Now I looked at your products and while I'm not experienced with the field I have abit of interaction with arcvis in unreal engine and from my perspective points #1 & 4 apply here while having no interior your models look abit too low poly and have sharp corner, sure different categories have different need but there is no harm in diversifying your horizon and make better products, hope that helped.
