> unless it is one of the device's primary function to transmit out

I'd argue that even in that case it should still "function" without public internet connection, in the sense that everything but the egress transmission should be operable without public internet connection; e.g initial setup, later configuration changes, status, diagnostics, maintenance... Many devices use the "it's a transmission device by design" part as an excuse for "let's blanket require connection even for things that don't require it".