Totally fair. Project Walt should help with some of that, but will still require you to replace the switch with a Zigbee one.
That said, even without a Zigbee switch, the external antenna will likely be good enough to get you a signal to your hub (assuming of course you don’t like in a house with metal / cinderblock / plaster walls and your house isn’t a giant mansion. Of course, your mileage may vary, but I think it’s worth a shot.