Megatron-UK

AEM do a range of 52mm AFR gauges that have a plain-old serial datastream output, so usable by virtually any data logger. They seem fairly quick to respond, too.

https://www.aemelectronics.com/produ...el-controllers

They also do just a lambda probe and datalogger, if you have no need of a gauge.
Not affiliated, just using one of their gauges on a Ford Cosworth twin cam.