Not sure if this exists, but..

I’m looking at buying an intra oral camera. Wired ones are cheapy cheap compared to wireless ones, plus i’m not sure how much use it will get so dont want to fork out ££££.

Is there a device that would plug into one end of a USB cable (ie from the camera) and transmit the data to a receiver on the PC?

You can get “usb print servers” which as the name suggests are for usb printers. Theoretically they should work as a remote usb relay, not sure I would risk buying such a specialized piece of equipment and expecting the software to work with such devices though.

Never seen one – but it’s a good idea!

I think this is what Bluetooth was invented for really, but of course that requires a bunch of different standards instead of hiding that detail and pretending to the PC that it is just a local device.