New Twiddle

components.counter\.js

import Component from '@glimmer/component';
import { inject as service } from '@ember/service';
import { action } from '@ember/object';

export default class extends Component {
  @service counter;
  
  get count() {
    return this.counter.count;
  }
  
  @action
  increment() {
    this.counter.increment();
  }
}

controllers.application\.js

import Controller from '@ember/controller';

export default class ApplicationController extends Controller {
}

services.counter\.js

import Service from '@ember/service';
import { tracked } from '@glimmer/tracking';

export default class extends Service {
  @tracked _count = 0;

  get count() {
    return this._count;
  }

  increment() {
    this._count++;
  }
}

templates.application\.hbs

<Counter />

templates.components.counter\.hbs

Count: {{this.count}}
<button {{on "click" this.increment}}>
  Increment
</button>

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"
  }
}