Create button with link in Yii2
You could simply use Html::a() :
<?= Html::a('label', ['/controller/action'], ['class'=>'btn btn-primary']) ?>
Or create your own version of Button
class to handle this.
PS: you don't need Url::toRoute
you can also pass parameter to url
<?= Html::a('Update', ['update', 'id' => $model->id], ['class' => 'btn btn-primary']) ?>
You can also render the html
<?= Html::a('<span class="btn-label">Update</span>', ['update', 'id' => $model->id], ['class' => 'btn btn-primary']) ?>