A sibling directory is not registered

[Nefcanto]

Consider this structure:

Core
    Tokenize.js
    Camelize.js
App.js
package.json

Try to register the Core as an alias dynamically, in the App.js file:

import * as path from "path"
import * as url from "url"

const __filename = url.fileURLToPath(import.meta.url)
const __dirname = path.dirname(__filename)
import moduleAlias from "module-alias"

const corePath = path.join(__dirname, "Core")
moduleAlias.addPath("/")
console.log(corePath)
moduleAlias.addAlias("Core", corePath)

import "module-alias/register.js"

import { camelize } from "Core"
console.log(camelize("Hello"))

You get this error:

node:internal/modules/esm/resolve:854
  throw new ERR_MODULE_NOT_FOUND(packageName, fileURLToPath(base), null);
        ^

Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'Core' imported from /HolismHolding/Generation/Generate.js
    at packageResolve (node:internal/modules/esm/resolve:854:9)
    at moduleResolve (node:internal/modules/esm/resolve:927:18)
    at defaultResolve (node:internal/modules/esm/resolve:1169:11)
    at ModuleLoader.defaultResolve (node:internal/modules/esm/loader:542:12)
    at ModuleLoader.resolve (node:internal/modules/esm/loader:510:25)
    at ModuleLoader.getModuleJob (node:internal/modules/esm/loader:239:38)
    at ModuleWrap.<anonymous> (node:internal/modules/esm/module_job:96:40)
    at link (node:internal/modules/esm/module_job:95:36) {
  code: 'ERR_MODULE_NOT_FOUND'
}

Node.js v20.18.1

This is a simple example. I'm trying to alias a lot of directories. I want to be able to write these imports:

import { camelize } from "Core"
import { getPosts } from "Blog"
import { createProduct } from "Products"
...

And each Core or Blog or ... is in a nested directory and they are dynamically added or removed (a CMS).
But even a simple setup as the above does not work.

What should I do?