Hi @sel,
Thanks for reaching out.
In fact, setting preview in Nuxt normally is pretty straightforward with the help of the Prismic-Nuxt preview module.
For me, if you can preview changes in published documents, then the issue can be related to a missing 404 fallback such as:
You can also check our troubleshooting thread for more information:
https://community.prismic.io/t/troubleshooting-previews
And please don't hesitate to reach back to us if you still have further inquires,
Fares