QPs

controllers.my-route\.js

import Controller from '@ember/controller';
import { tracked } from '@glimmer/tracking';

export default class extends Controller {
  // This is where Query Params need to be configured.
  
  // queryParams = ['foo'];
  
  @tracked foo;
}

router\.js

import EmberRouter from '@ember/routing/router';
import config from './config/environment';

const Router = EmberRouter.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('my-route');
});

export default Router;

routes.my-route\.js

import Route from '@ember/routing/route';

export default class extends Route {
  // You can't configure them here...
  // queryParams = ['foo']
  
  // ...unless you want to do:
  queryParams = {
    refreshModel: true
  }

  // Ah ha, you can do this:
  queryParams = {
    foo: true
  }
}

templates.application\.hbs

Application:

<br><br>

<LinkTo @route="my-route" @query={{hash foo="bar"}}>
  MyRoute
</LinkTo>

<br><br>

{{outlet}}

templates.my-route\.hbs

MyRoute:

<br><br>

foo: {{this.foo}}

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"
  }
}