Gave up on the 8bitmo dongle and SN30 Pro combo. Could only get a wired connection to work which is entirely pointlessUpdate
SN30 Pro wired connection via Anker 4 port works well. Select "X-input" setting and away you go. Dashcam thumb drive also working
Wireless via 8bitdo Adaptor 2 not so much. Have followed "X-input" set up on Adaptor, the controller successfully connects to adaptor but cannot get car to recognise the controller is connected. Sonic "play game" button is greyed out
Might swap the 8bitdo 2 for the original 8bitdo version adaptor as a last try. If that fails just revert to cheapo wired controllers
Replaced with EasySMX Wireless Game Joystick Controller - thanks @Sparky750 - which has included dongle and controller for £21. Worked right out of the box wirelessly. Easy peasy