How to upload, maintain, & update Assets that cannot be on the network

BRIEF OVERVIEW

Hi everyone, I have an issue. My company is trying to move its assets management data to Spiceworks. This was previously managed using an excel sheet. My company is an MSP and we are looking to also introduce this to our client tenants. Also, we would like to be able to monitor the inventory of the clients as well for documentation.

OBSERVATION

I have tested the Spiceworks asset manager, did a network scan of inventory and I have seen all the detailed goodness it can provide for managing devices that can be connected on the network, for example, printers, laptops, desktops, scanners, copiers, mobile phones, etc.

PROBLEM

But my problem is about devices that cannot be on the network, for example, physical tools, chairs, desks, appliances, cables, etc. and other stuff that are in an office but are not able to be put on the network. How are these managed in Spiceworks asset manager?

QUESTIONS

Is it possible to manage devices that are not connected to the network in Spiceworks asset manager?

How do I upload these OUT-OF-NETWORK items to the database?

how are these OUT-OF-NETWORK item records in the database updated and maintained? (for example, I want to state that this specific laptop disconnected from the network was upgraded from a 4gig ram to 8gig, or a vendor serviced an appliance on a given date and is due for servicing on another given date)

Also, does this mean only one administrator gets to update the database for the various department's inventories that are in the company? or how do the various department have access to update the inventory for their various teams?

If possible, how can this solution be deployed by an MSP to tenants and how can tenants' various department database assets be maintained both at their location and centrally from our company (the MSP)?

If this cannot be achieved by Spiceworks, is there any solution to achieve what I'm asking for??

Any assistance available will be highly appreciated