Hi @drmonalisa, thank you for the clarification. In this case, your method would seem to be appropriate as a means to test if there is either 4C or ET5 Tobii Core software installed. An alternative might be to iterate over connected windows devices but this would not guarantee that the correct drivers and SW are installed so your approach would seem to be the most logical. And yes, the service should always be running if the drivers have been installed (for both trackers).
Do let us know if we can provide any further assistance. Best Wishes.