Enqueue Stylesheet on the front end and in the block editor Conditionally

This can be done. @TomJNowell does point out the potential for a problem with this solution in the comments to the question but I cannot replicate that problem in any test.

In this example I locked on to the template slug. Therefore for this to work instead of using is_front_page() or similar, create a template called homepage and use it only for the homepage. Then do the same for any other pages you want to have a custom stylesheet.

add_action('enqueue_block_assets', function () {

  global $post; 

  $template = get_page_template_slug($post->ID);

  wp_enqueue_style(
    $template . '-template-styles',
    get_template_directory_uri() . "https://wordpress.stackexchange.com/" . $template . '.css',
  ); 

});