Is it possible to add inventory/stock details to the products in Zoho CRM?
No, it is not possible to enable inventory tracking for a product in Zoho CRM. It has to be done in your Zoho Books organization. Once inventory tracking is enabled for an item in Zoho Books, the stock will reflect under the Zoho Finance Information section for the item in CRM.
Note: Zoho CRM only displays the Accounting stock and not the Physical stock for a product.