In order to build on top of the same foundation and to save time, I think that we should reuse the existing build steps of the main repository by leveraging Babel. It appears that reproducing the same building pipeline will provide the maximum consistency. For instance

• we would like to remove the requirement from yarn link & yarn build in order to work on the documentation or the storybook.
• we will likely want to keep the same production optimizations: https://github.com/mui-org/material-ui/blob/2ed7b23dc35cf72265065506e406427dbcf06a77/babel.config.js#L35.
• we would like to rely on our browserlist to guarantee browser support, something TypeScript doesn't support Suggestion: target specific runtimes instead of JS versions microsoft/TypeScript#19183
• we don't want to minimize the source in the npm package