currentRouteName

components.my-component\.js

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

export default class extends Component {
  @service router;
  
  @alias('router.currentRouteName') currentRouteName;
}

controllers.application\.js

import Controller from '@ember/controller';

export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';
}

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('parent', function() {
  	this.route('child');
  })
});

export default Router;

routes.parent.child\.js

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

export default Route.extend({
});

routes.parent\.js

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

export default Route.extend({
});

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
{{my-component location="application route"}}
<br>
{{outlet}}
<br>
<br>

templates.components.my-component\.hbs

<div>
  Location: {{@location}}
  <br>
  currentRouteName: {{this.currentRouteName}}
</div>

templates.parent.child\.hbs

<div style="border: 1px solid gray; margin: 10px">
  {{my-component location="Child Route"}}
  <br>
  {{outlet}}
</div>

templates.parent\.hbs

<div style="border: 1px solid black">
  {{my-component location="Parent Route"}}
  <br>
  {{outlet}}
</div>

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",
    "ember-data": "3.8.1"
  }
}