I found a thread from 8 years ago about this as well, and although there was an answer provided-it only gains you a report of customers that a given item was sold to.

What I'm interested in is the opposite--I know the customer, but I want to report on all inventory items that have been sold to that customer. For example, if I sold them a device sometime a year ago and I need to see the make/model of the device--I wouldn't already know the inventory item SKU, but I would know that it is for customer X.

Currently having to open each invoice to find the item-a very painful process as most customers also have ticket, projects, and subscriptions also being invoiced which makes it even more difficult to find the right invoice that has the particular item on it.