New Twiddle

components.my-component\.js

import Component from '@glimmer/component';
import { action } from '@ember/object';
import { tracked } from '@glimmer/tracking';

export default class extends Component {
  get value() {
    if(!this.args.value) {
      return '';
    }
    if(Array.isArray(this.args.value) && this.args.value && this.args.value[0] === 'm') {
      return 'm';
    }
    return this.args.value;
  }
  
  @action
  check(event) {
    if(event.target.value === 'm') {
      this.args.update(['m']);
    } else {
      this.args.update(event.target.value);
    }
  }

	@action
	clear() {
    this.args.update(null);
  }
}

controllers.application\.js

import Controller from '@ember/controller';

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

helpers.eq\.js

import { helper } from '@ember/component/helper';

export default helper(function eq(params/*, hash*/) {
  return params[0] == params[1];
});

templates.application\.hbs

<MyComponent @value={{this.value}} @update={{fn (mut this.value)}} />

templates.components.my-component\.hbs

<input type="radio" id="foo" value="m" checked={{eq this.value "m"}} {{on "click" this.check}}>M
<input type="radio" id="bar" value="f" checked={{eq this.value "f"}} {{on "click" this.check}}>F
<input type="radio" id="bar" value="d" checked={{eq this.value "d"}} {{on "click" this.check}}>D

<button {{on "click" this.clear}}>clear</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"
  }
}