Modul menu_link_attributes installieren und wie folgt konfigurieren:

menu_link_attributes.yaml

attributes:
  class:
    label: ''
    description: ''
  data-icon:
    label: Menu-Icon
    description: 'Set an Icon for this menu-entry.'
    options:
      icon-academic-cap: Academic-Cap
      icon-newspaper: Newspaper
      icon-pencil: Pencil
      icon-at-symbol: at-Symbol
    default_value: ''
  target:
    label: ''
    description: ''
    options:
      _blank: 'New window (_blank)'
      _self: 'Same window (_self)'
    default_value: ''
  rel:
    label: Rel-Attribute
    description: 'Rel(ation) Attribute festlegen'
    options:
      nofollow: nofollow
    default_value: ''

Theme Hook für Menu-Entries in der Datei TemplateName.theme bereitstellen und das „FormattableMarkup“ nach eigenen Wünschen gestalten.

templatename.theme

/** fuer menu_link_attributes:
 * svg icons als svg sprite bereitstellen
 * passendes sprite auswaehlen
 * svg in page.html.twig
 */
 use Drupal\Component\Render\FormattableMarkup;
 
 /**
  * Implements theme_preprocess_menu().
  */
 function swiftly_preprocess_menu(&$variables, $hook) {
   foreach ($variables['items'] as &$item) {
     $attributes = $item['url']->getOption('attributes');
     if (isset($attributes['data-icon'])) {
       $title = new FormattableMarkup('
        <div class="flex gap-1 items-center">
         <svg class="icon @icon" viewbox="0 0 24 24"><use xlink:href="#@icon"></use></svg>
         <span class="hidden md:block">@title</span>
        </div>
       ', [
         '@title' => $item['title'],
         '@icon' => $attributes['data-icon'],
       ]);
       $item['title'] = $title;
     }
   }
 }

Die SVG-Icons als SVG Sprites in der Datei page.html.twig (immer verfügbar) bereitstellen, einfach unten anfügen. Die Icons selbst sind in diesem Fall von heroicons.com.

page.twig

<svg class="hidden">
	<defs>
		<g id="icon-newspaper">
      <path stroke-linecap="round" stroke-linejoin="round" d="M12 7.5h1.5m-1.5 3h1.5m-7.5 3h7.5m-7.5 3h7.5m3-9h3.375c.621 0 1.125.504 1.125 1.125V18a2.25 2.25 0 01-2.25 2.25M16.5 7.5V18a2.25 2.25 0 002.25 2.25M16.5 7.5V4.875c0-.621-.504-1.125-1.125-1.125H4.125C3.504 3.75 3 4.254 3 4.875V18a2.25 2.25 0 002.25 2.25h13.5M6 7.5h3v3H6v-3z" />
		</g>
 
    <g id="icon-academic-cap">
      <path stroke-linecap="round" stroke-linejoin="round" d="M4.26 10.147a60.436 60.436 0 00-.491 6.347A48.627 48.627 0 0112 20.904a48.627 48.627 0 018.232-4.41 60.46 60.46 0 00-.491-6.347m-15.482 0a50.57 50.57 0 00-2.658-.813A59.905 59.905 0 0112 3.493a59.902 59.902 0 0110.399 5.84c-.896.248-1.783.52-2.658.814m-15.482 0A50.697 50.697 0 0112 13.489a50.702 50.702 0 017.74-3.342M6.75 15a.75.75 0 100-1.5.75.75 0 000 1.5zm0 0v-3.675A55.378 55.378 0 0112 8.443m-7.007 11.55A5.981 5.981 0 006.75 15.75v-1.5" />
    </g>
 
	</defs>
</svg>