Configurations in the Container

components.my-component\.js

import Component from '@glimmer/component';
import { inject as configuration } from '../utils/configuration';

export default class extends Component {
  @configuration
  myConfiguration;
  
  get sameConfiguration() {
    return this.args.configuration == this.myConfiguration;
  }
}

configurations.my-configuration\.js

import Configuration from '../utils/configuration';
import { inject as service } from '@ember/service';

export default class MyConfiguration extends Configuration {
  @service
  myService;
  
  get options() {
    return [
      this.myService.getOption(0),
      this.myService.getOption(1)
    ];
  }
}

controllers.application\.js

import Controller from '@ember/controller';
import { inject as configuration } from '../utils/configuration';

export default class ApplicationController extends Controller {
  @configuration
  myConfiguration;
}

services.my-service\.js

import Service from '@ember/service';

export default class MyService extends Service {
  getOption(idx) {
    return {
      name: `Option ${idx}`
    };
  }
}

templates.application\.hbs

{{#each this.myConfiguration.options as |option|}}
  <p>{{option.name}}</p>
{{/each}}
<MyComponent @configuration={{this.myConfiguration}} />

templates.components.my-component\.hbs

<p>
 The configuration is really a singleton: {{sameConfiguration}}
</p>

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}

utils.configuration\.js

import { getOwner, setOwner } from '@ember/application';

/**
 * Base class that matches the containers expectations of a static create method that it will use to instantiate an instance of the class when a lookup is performed
 * For an example of an actual configuration class see configurations/my-configuration.js
 */
export default class Configuration {
  static create(something) {
    const configuration = new this();
    setOwner(configuration, getOwner(something));
    return configuration;
  }
}

/**
 * inject property decorator that can be used just like the service inject decorator, but for looking up classes in the components directory instead of the services directory
 */
export function inject(clazz, propertyName, config) {
  config.initializer = function() {    
    return getOwner(this).lookup(`configuration:${propertyName}`);
  }
  return config;
}