Let's say that the professional business router is connected to the Internet through the WAN port and has some devices in the office connected through the other ports.

The devices in the office building have internal IP addresses and only the router has an external IP address.

Can it be said that the router performs actual routing or only does NAT?

It does not seem that the router performs any routing at all.

The devices in the office have only internal IP addresses and inside the business there is no subnet, so the user only has one external IP address which is take by the router's external connection to the Internet?

So is it an exaggeration to say that a business router for an office is a router?

Do most business routers have the actual capability to even do routing or they can only do NAT?