component-aggregator-definition.js

const componentReferences = {};

@customElement('component-reference')
export class ComponentReference extends LitElement {
  @property() name = '';

  render() {
    const refs = componentReferences[this.name] || [];
    const content = refs.map(r => `<${r}></${r}>`).join('');
    return html([content]);
  }
}