Hi,
I did it with a pseudo element:
.product[class*="dalle"] .stock::before, .product[class*="pave"] .stock::before{
content:"m2 : ";
}
With this CSS snippet, only the product in the category “Pavé” or “Dalle” will display “m2” next to the stock. You should be able to use this and replace the unit of mesure value and your categories. It’s not the best way to do it, but it solves this.
I hope it will be possible to display the unit of mesure there in a future update.
Best,