theming – how to programmatically display a view embedded in code with a template

I have a page I’m generating in a module. I’m using this code to get a block from a view:

$block = views_embed_view('testimonials', 'block_1');
$view = Drupal::service('renderer')->render($block);
$my_block = $view->__toString();

and display it in the generated HTML:

<div class='testimonials'>$my_block</div>

When I view the page in a browser and inspect it (with twig.debug=true), I don’t see the output rendered by a block template. If I display the block in a region by using the block layout page, I do see there is twig involved.

What do I have to do to make it use a template when I create the block in code? I think the correct answer would be to create a twig template for the entire page, and pull the block into the page template. But I’m curious if it could also be done this way.