Hi @haramchoi, you can use the Tobii XR SDK freely with the HTC Vive pro eye for which we provide instructions @
https://vr.tobii.com/sdk/develop/unity/getting-started/vive-pro-eye/
I’m afraid Ocumen does not support the HTV Vive Pro Eye, but you have the G20M module included with the XR SDK that should give you the dwell time, etc.
Check out the included samples and let us know how you get on. Best Wishes.