Serviceable items simply refer to items that do not need repairs or refurbishing; they operate satisfactorily, or we can say they are functional. Some things should not be the factors that determine whether an item operates satisfactorily or is functional, such as age or obsolescence.
Serviceable items can be very old or obsolete. Serviceable item is actually a term used in the law field and not actually a different English word. If we want to explain it with the knowledge of English, we would probably say that a serviceable item is an item that can be serviced.
Hence, any good company ensures that they deliver serviceable items through whatever delivery medium to their customers. However, most serviceable items are usually big items rather than small items. Hence, an item can be said to be an unserviceable item when the customer discovers a fault and returns it to the delivery agent.