We've project using technology stack - Nuxt JS, Prismic using @nuxtjs/apollo, I've done Preview settings in our Prismic Repo and of course have added 'prismic.js' in head section, but when I try to see preview I'm getting 'Page Not Found' error.
Because there is a route '/preview' in url and as per my understanding the script prismic provides (to inject in head section) handle this route and then preview are shown.
But in my case, I'm getting Page Not Found (404) error.
I'll be very happy to help you with this. Although I've never implemented previews with @nuxtjs/apollo, I'll still be willing to check it out.
Since you're hitting the 404 page, it sounds like maybe you haven't included the preview script in the head of the 404 page as well. We discuss this and more possible preview issues here:
If that doesn't work I'll be happy to check this out for you, if you can forward me the github to your project I'll check it out. (You can do this in a private message if you wish.)
I had a look and I think I might know what the issue is. Normally the @nuxt/prismic module automatically builds a /preview route in the pages directory for you, but since you're not using the module there is no corresponding route which should re-direct your application to the correct page on which to load the preview cookie.