Are ES modules supported in Ember CLI addon blueprints?

Can I use ECMAScript modules in Ember CLI addon blueprints?

The blueprints of one of the addons I maintain (ember-bootstrap) depends on another package (chalk) which is shipped as an ECMAScript module in recent versions. Wonder if there is any way to upgrade.

What I tried out but didn’t succeed:

  1. Convert to static import treating the file as an ECMAScript module.
  2. Dynamic import() with top-level await.

Both failed. But I haven’t deeply looked into it. Wondering if any of them is officially supported. Or should we stay with legacy CommonJS modules for now?