no-controller

routes.application\.js

import Route from '@ember/routing/route';
import { tracked } from '@glimmer/tracking';
import { action } from '@ember/object';

export default class ApplicationRoute extends Route {
	@tracked foo = 'foo';

  get bar() {
    return `${this.foo} bar`;
  }

  model() {
    return {
      foo: this.foo,
      bar: this.bar,
      helloWorld: this.helloWorld,
      updateFoo: this.updateFoo
    };
  }

  @action
  updateFoo(event) {
    this.foo = event.target.value;
  }

  @action
  helloWorld() {
    console.log('hello world:', this.bar);
  }
}

templates.application\.hbs

<h1>Welcome to {{@model.foo}}</h1>
<br>
<input value="{{@model.foo}}" {{on "input" @model.updateFoo}}>
<br>

{{@model.bar}}

{{outlet}}
<br>

<button {{on "click" @model.helloWorld}}>Say hello</button>
<br>

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": {
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0",
    "ember-simple-set-helper": "0.1.2"
  }
}