swagger code generation using version 3 for language typescript-node

The code generation for typescript-node has changed from swagger 2 to swagger 3.
Swagger 2 creates client code in a single file, whereas swagger 3 is creating multiple file and subfolders.
This is causing now unresolvable problems when trying to put that code into a typescript module.

When using import in files residing in folders there are two errors happening:
Not specifying "type": "module" in package.json causes the error "can not import outside of a module".
Specifying "type": "module in package.json causes the error "[ERR_REQUIRE_ESM] Warning: require() of ES modules is not supported. require() of ..."

Researching this issue, seems to point the fact, that the code has to reside in one file, to be usable as a module.

Am I missing something ?
I understand that the code structure is far better in separate files, but this is a blocker to me to use swagger 3 codegen.

Start with the typescript-node code-generation entry point and its generated package.json/module configuration; the issue does not name specific template files or tests. Reproduce the import failures with Swagger 3 output, then determine whether the generated structure can be used as a TypeScript module and document the expected behavior.