You can create a Google form that does not require signing in to Google (that is, the user can fill in the form anonymously).
Here are the steps.
Go to Google forms website and create a new blank form
Press the new blank form button:
Go to the settings by clicking on the ‘settings’ icon on the top right
Make sure that all the options that require sign up are unchecked.
You can test whether the form works without any Google Sign in. Open a browser where you never sign in to Google (open Firefox, Opera, Safari where there is no automatic Google Sign in)
In Google forms, click the “Send” button and copy the short link to the form Paste the link in the browser you have opened.
Then see that the form works without Google sign in: