How to use path alias or exportPathMap with next build

[maximgeerinck]

I would like some routes to have aliases for SEO.

For this i'm looking to something that does exactly what exportPathMap does but then when using next build instead.

I tried adapting the router of the context in the getInitialProps on _app but it doesn't seem to take any effect.

so for example, /hello should render the page that's also on url /hey where hey is a file under pages/hey.js