Rendering static JSON at build time?

[RobRoseKnows]

I'd like to build an API using Next.js, but some of the data returned by my API is static, so I'd like to generate the JSON at build time rather than using the api/ route. I've already found this discussion, but it looks like they ended up using the api route and the getInitialProps answer doesn't seem like it would let me use getStaticPaths and getStaticProps as well. My ideal use would be defining a path under pages and returning raw JSON and getting JSON (not an HTML page with JSON in it).