Change Asset Product Type

Is there a way to change the product type for an asset that is not of type "workstation" or "server"?

We'd like to create a new product type and transfer one or more existing assets into the new product type. I know we can change the product type for a workstation (ex. change it to a server), but I do not see a way to do this with our own product type names.

Ex. We want to create "Firewalls" as a product type and changes several existing "Routers" product type assets to a Firewall. There is no option to change the product type here.

Deleting the existing asset, then re-creating it as a new asset with a product type of "Firewalls" is *technically* an option, but not a realistic or valid (IMO) option.

Renaming "Routers" to "Firewalls" would be an option, but:

Routers is a built in product type and not editable
We have assets that are routers only too, so we'd still then have to create a custom product type of "Routers" and we're back to square one with the same situation we have now where we can't change the product type of Firewalls to Routers.

Yes, it is livable to keep our firewalls listed as a "Routers" product type, but I can foresee other scenario's where this might not be ideal as well as other customers wanting to do the same thing.