The "cheating device" was just a feature flag that could be enabled on the engine computer made by Bosch, who also makes engine computers with similar software for most other car companies. Bosch told them about the feature, educated them about what it would do, what it would mean, how it's not really legal etc, and then Volkswagen decided to turn it on.
Bosch sells engine hardware (ECU, pump, injectors etc..), but the software is custom made. The automaker pays Bosch to implement the SW they want, as a lot of features differentiating automakers are SW features that they do not want their competitors to have.
Hence it doesn't mean that every diesel engine with a bosch ECU had the cheating device from VW.
