My brother had a Tobii eye tracker for a couple years. I think it was the 3 model? It worked well enough. He gave it away cause he got a large ultrawide monitor that it couldn’t work right with.
He used it in a couple games that supported it that we were playing at the time (Division 2, Vermintide) and also used it when screen sharing doing training activities as it would display a small halo to show where he was looking.