Integrate Google OAuth process into my custom Safari extension

I'm looking to integrate the Google OAuth process into my custom Safari extension, but I haven't been able to find specific documentation on how to do this, similar to what's available for Chrome extensions. After some research and testing, I've tried using both browser.identity.getAuthToken and safari.identity.getAuthToken, but neither seems to be working. I'm wondering if anyone can provide a solution for this issue. The extension works fine in Google Chrome, but not in Safari.

Below is the code I'm currently using for Safari:

`browser.identity.getAuthToken({ interactive: true }, function (token) {
        localStorage.setItem("accessToken", token);
    });`

Is there any documentation available for using the Google OAuth process in my custom Safari extension, Because I am not able to found anything related to it?

Could someone please inform me of any mistakes I might be making here?