This repo is a copy of an official example approach combining few suggestions. Refections are documented into this article about Gatsby i18n.
https://using-i18n.netlify.com/
Example site that demonstrates how to build Gatsby sites with multiple languages (Internationalization / i18n) without any third-party plugins or packages. Per language a dedicated page is built (so no client-side translations) which is among other things important for SEO.
The general information are defined in config/i18n.js, the translations are located in config/translations. The custom hook useTranslations pulls in these translations then (when the former is changed, the latter needs to update its GraphQL query). Due to the usage of a global layout/Context API and the passed locale to all pages (see gatsby-node.js) you know on every page which language is currently displayed. Moreover, with the usage of MDX and gatsby-mdx a custom component for the <a> tag is implemented -- this way links can stay the same for every language, without the need to manually write path prefixes.
Opinionated choices that were made:
blog. The folder names are the slug of the page. Inside these folders there has to be an index.mdx file (for the default language). Any other language needs to be defined in the format name-with-dashes.lang.mdx