Adding multiple links to the same table cell
I think you can do it as Clive alluded to with render array:

  $link_1 = Link::createFromRoute('Link 1', 'route_1')-&gt;toString();
  $link_2 = Link::createFromRoute('Link 2', 'route_2')-&gt;toString();
  $link_concat = ['#markup' =&gt; $link_1 . ' - ' . $link_2];

  $header = [ ... ];
  $row = [];
  $row[] = [
    'data' =&gt; \Drupal::service('renderer')-&gt;render($link_concat),
    'class' =&gt; 'middle',
  ];
return [
  '#theme' =&gt; 'table',
  '#header' =&gt; [..],
  '#rows' =&gt; $row,
];


This is just one method of doing it, there are a lot of ways you could potentially work this scenario. This way just puts the two links with a dash in between. But hopefully this will help guide you towards a solution.