Air fuel ratio gauge options

I know this is not what you are looking for. I used a similar narrow band for tuning dual IDF Webers on offroad VW's years ago. Velcroed in place while sorting out the carbs then back in the tool box.
NTK 90067 AFX Air/Fuel Ratio Monitor Kit

FAST also makes a wireless a/f setup. not cheap.

FAST Wireless Air/Fuel Meter - Single Bank | 170301

AEM also made one, now discontinued.