Thanks for the response @roman_r_m
Next.js Will also build a static site. I checked the Joplin-docs, the UI looks great, It is great from a user point of view, but from a developer's, don't you think React.js is mostly used and better to maintain by the community. Big projects like ChakraUI, React Docs,Tailwind uses Next.js
For the Lib use
MDX allows to use React Components in the markdown file.
Jest and Cypress are just for testing the codebase.
I want to use Next.js because it contains some cool features like
Image Optimization for faster site load.
Internationalization(Built-in Domain & Subdomain Routing
and Automatic Language detection.) If in future we use it
Static site generation as you said
File-system Routing
and lots of more stuff.