It's confusing for me because there is really expensive AFR like Autronic Exhaust Gas Analyzer (~$1600) and then relatively cheap ones. Then you have to understand the probes. Then there is narrowband and wideband. Quite confusing.
I *think* my understanding is something like the Innovate product is a pretty good bit of kit. Maybe not for professional tuning, but at least for keeping an eye on things.