Dynamically determine existence of template only Ember glimmer component?

I know that to dynamically determine the existence of a component on Ember we can use the solutions explained here or here.

We have a helper that uses .hasRegistration('component:${component}')

This also works for Glimmer components as long as there is a .js file defined, but it doesn't work for template-only Glimmer components. The component doesn't seem to be registered in that case.

Does anyone know a solution that would work for template-only glimmer components too?

I made a demo for you over on stackblitz:

https://stackblitz.com/edit/github-k7htnb?file=app%2Fcomponents%2Fdemo.hbs

{
  "component:template-only": true,
  "template:template-only": false
}

here is the code showing that what you're doing works in Ember 3.28:

<pre>{{this.format this.results}}</pre>

import Component from '@glimmer/component';
import { tracked } from '@glimmer/tracking';
import { getOwner } from '@ember/application';

export default class Demo extends Component {
  format = (data) => JSON.stringify(data, null, 2);

  @tracked name = 'template-only';

  get results() {
    let owner = getOwner(this);
    let name = this.name;

    return {
      [`component:${name}`]: owner.hasRegistration(`component:${name}`),
      // added this for curiosity
      [`template:${name}`]: owner.hasRegistration(`template:${name}`),
    };
  }
}

Now, if I change the ember-source to 3.26.1, it's the same.

Maybe there is a slight code mismatch between what you're doing and what this demo is doing?