Transpiling local package dependencies that use TS file as entry point

Hi, consider a monorepo that has some TypeScript packages kept in packages/*. Now one of these packages, let's call it b, depends on package a. Package a has entry point set as TS file e.g. src/index.ts.. When trying to bundle such package microbundle fails since it cannot transpile package a as it's declared as a dependency of b and thus it's expected that the package is already bundled up.

I could think of the following solutions:

1. Only use published npm packages as dependency.
2. Always point main entry to bundle e.g. dist/index.js.
3. Keep using TS files as main entry but when bundling, use bundled version i.e. dist/index.js.

I have prepared a small sample monorepo illustrating the issue https://github.com/karolisvram/packages-publishing-sample/ but so far haven't decided on the best solution as all have drawbacks. Ideally, mirobundle would transpile its local dependencies too but as far as I can tell, it's not supported? Any there any other alternatives that I'm missing?