Good day, MJ01.
Yes, you're right. QuickBooks Desktop Enterprise 2014 and later versions let you add up to one million names (customers, vendors, and employees) and a million items as well (inventory, non-inventory, and service). This includes the active and inactive names and items already.
I've got you an article that you can check: Maximum number of list entries (list limits and custom fields).
Feel free to drop a comment if you have more questions. Have a nice day!