Hello,
I’d recommend asking your question in TypeForm’s help center for more information on how to pass hidden values.
If you wanted to integrate TypeForm to your Wix site you can always try embedding your form.
You can also look to see if TypeForm exposes a REST API on their platform. This would allow you to use fetch to pass data between the platforms. Take a look at this article on accessing 3rd party services:
https://support.wix.com/en/article/accessing-3rd-party-services
Best regards,
Miguel