After reviewing the thread you referenced about using the Tobii 4c, it sounds like the issue maybe a licensing one, not a psychopy.iohub one. I found this post from tobii explaining why the Tobii 4c does not work with the tobii_research package and what you would need to buy to make it work I guess. So this is definately, at least in part, a Tobii licensing issue.
I still have my two Tobii: 4C and X. Are use a Mac with Catalina. The person who started this post didn’t say.
Bill Prinzmetal
(510)685-8623
billprinzmetal@gmail.com
When going to test the eye trackers on Catalina, I clued into the fact that there is no network port on my new macbookpro, duhhh. 
I’ve order one that connects to a USB C port. Once I get it I can check the eye tracking demo’s on Catalina (by early next week). I’m using an Anaconda3 Python 3.6 env. so once I can confirm the eye tracking demos work it should not be too hard for you to reproduce the environment on your machine.
Do you know if the Tobii 4C is supports using the tobii-research python package? We should check that as well.
Thanks again.
Sol,
I think you are correct about the 4C license issue. I spent months stupidly trying to get one to work. So I bought a Tobii X (used on EBay) but never got to try working with it. Health issues started to take most of my time.
Occasionally I help a student in my adopted lab (Dr. David Whitney) with a PsychoPy program, but not eye movements,
Bill Prinzmetal
(510)685-8623
billprinzmetal@gmail.com
I can not say for sure. I found a really old posting on PsychoPy that said IOHub would not work with Tobii 4C. I do not remember the reason but I assumed it had something to do with the licensing.
Bill Prinzmetal
(510)685-8623
billprinzmetal@gmail.com
Here is a link that lists the eye trackers supported by the tobii pro SDK / tobii-research package and therefore what should work with psychopy.iohub. It does not look like the 4C is supported. I’ll update the iohub tobii interface docs and point to the tobii docs page.
Thank you.