How to build different js bundles using Common Components (ES6 modules) if these modules have external dependencies?

Question

JavaScript

I don’t understand how to use common es6 modules (from my own module library, for example) when you need to build 2 different js bundles from them (for example, for the desktop and mobile versions of the site). In a situation where these shared modules have external dependencies .
Let's say we need to implement a button repainting in blue when clicking on it.
The structure of the modules in a simplified form is as follows:

// ===== mainMobile.js - главная точка входа

import Button from './button.js';

let colorMain = 'blue';
new Button(document.querySelector('.button'));

export { colorMain }

// ===== button.js

import { colorMain } from './mainMobile.js';

export default class Button {
  constructor(elem) {
    this.elem = elem;
    this.elem.addEventListener('click', () => { this.paint(); })	
  }

  paint() {
    this.elem.classList.add(`button_${colorMain}`);
  }
}

I specify the webpack entry point - mainMobile.js - the bundle builds fine.
Now let's say we need to build another bundle (for desktop). Desktop has minor differences (for example, when a button is clicked, it turns green instead of blue).
I create a mainDesktop.js file that is similar to mainMobile.js. For a desktop button, I want to use the already existing button.js module.

// ===== mainDesktop.js - главная точка входа

import Button from './button.js';

let colorMain = 'green';
new Button(document.querySelector('.button'));

export { colorMain }

And I'm running into a problem . In the general button.js module, I need to import the colorMain variable, but from where? In the assembly for mobile, it must be imported from mainMobile.js, in the assembly for desktop - from mainDesktop.js.
How to differentiate? At the js code level or at the webpack build config level? No understanding
First, I assume that dynamic imports can somehow help , but I can't figure out how to use them.
Secondly, I assume that my initial approach may be wrong (when I basically export something to modules from the main entry point). But what's the alternative?