I am using a tsx to run apps in a nx monorepo with cross-env NODE_ENV=local tsx watch --tsconfig apps/xyz/tsconfig.app.json apps/xyz/src/main.ts. This works fine without any problems.

Now I try to build the same app with pkgroll as suggested in the tsx docs. The command I use is pkgroll --tsconfig apps/xyz/tsconfig.app.json --sourcemap --env.NODE_ENV=production apps/xyz/src/main.ts.
Now I am always getting the error Error: No export entries found in package.json. What do I have to put into the package.jsons exports that this works in a nx monorepo?