I have the same issue, the only way that I found to make my local packages work with NextJS is by import packed package.

• Run npm pack on the package to export, this create a package-version.tgz file.
• Then install it on the package, there is two ways:
  • npm install '/path/to/package-version.tgz'
  • Or add the dependecy "@my-libs/a-lib": "file:../../../a-lib-1.0.0.tgz", then run npm install