> - The standard typescript builder can only generate ES2018
That's true, but only because the compilation to previous ES versions is meant to be handled by other plugins. For instance, the "web" plugin [1] uses babel-preset-env, which in turn will take your package.json's "browserslist" [2] into account.
> - The web bundler can only generate ES modules
The Pika project seems to be all about promoting ES modules, so it's no wonder that put this option to the forefront. However, there is also an UMD plugin [3] and a "node" (presumably Common.js) one [4].
[1]: https://github.com/pikapkg/builders/tree/master/packages/plu... [2]: https://github.com/browserslist/browserslist [3]: https://github.com/pikapkg/builders/tree/master/packages/plu... [4]: https://github.com/pikapkg/builders/tree/master/packages/plu...