I’m using the IoT from Amazon that’s pretty commonly used:
I found this:
Something like this. In one position it would be turned on and off by the IoT. The other position would always have power. So, flipping the switch would turn on the vac; flipping it back gives control back to the IoT.
This switch is expensive though & I’m guessing that it might be because having two power sources connected is dangerous, & this handles that properly. If this is what it costs it would be cheaper to just buy another vacuum, which I could then carry around the shop where the dust hose won’t reach.