Identify Google Sign Up vs. Email Sign Up: WixUsers

I want to force users to sign up with Google, and reject users who signed up with email.

First off, is there a way to disable email sign up, only providing Google??

Or the other option, identifying the source of the registration to do email verification for those who didn’t use Google.

I’m trying to make a poll where users can only submit the form once, but I also only want real users to be able to fill out the form (which I can verify with Google), rather than anyone typing in random emails for random accounts.

By using a custom sign-up form you can provide a standalone Google login. The button would need to be custom coded to point to the right URL.

Here is the link to Wix article on custom forms:
https://support.wix.com/en/article/creating-a-custom-signup-form-for-your-members-area

There is a bit more information in this thread, including a code example.
https://www.wix.com/corvid/forum/community-discussion/login-using-facebook-button

Firstly, that link takes the forum poster to the custom form from Wix, which is provided by Wix Forms.

If you want complete control and to make up your own lightbox, then use the Corvid method out of the three options.
https://support.wix.com/en/article/about-the-member-signup-form#corvid-form

Plus, if you do your own lightbox, you will need to change the signup settings to suit too.
https://support.wix.com/en/article/corvid-enabling-custom-site-registration

See here for previous post with example code and links for more help on it.
https://www.wix.com/corvid/forum/community-discussion/custom-member-signup

Wix also do an example to about it.
https://support.wix.com/en/article/corvid-tutorial-creating-a-custom-registration-form-with-code

As for the Google only signup, well as you asked for Google, see here,
https://www.wix.com/corvid/forum/community-discussion/solution-google-facebook-user-information-on-login