Splitting data between table and drop-down menu Yii2

I have a task to make the following functionality:

The case is I need to be able to add to the table below items from the drop-down menu, so they should be either in drop-down (if tag is not added to the Material model) or in the table (if tag is added). I could easily hard-code it, but it’s also required Add(big blue button) button to add tags and delete button to remove them, which I have no idea how to implement. Tags are stored in another model which has no relation to Material, tags in Material are stored as a string divided by comma. Here’s what I’ve managed to do so far:

Controller:

public function actionView(int $id): string
    {
        $tagSearchModel = new TagSearch();
        $tagDataProvider = $tagSearchModel->search($this->request->queryParams);

        $model = $this->findModel($id);
        $tagsInModel = explode(', ', $model->tags);

        $tag = new Tag();
        $allTags = ArrayHelper::map($tag::find()->all(), 'id', 'name');

        $unUsedTags = [];

        foreach ($allTags as $oneTag) {
            if (!in_array($oneTag, $tagsInModel)){
                $unUsedTags[] = $oneTag;
            }
        }

        return $this->render('view', [
            'model' => $model,
            'unUsedTags' => $unUsedTags,
            'tagDataProvider' => $tagDataProvider
        ]);
    }

View:

<div class="col-md-6">
        <form>
            <h3>Теги</h3>
            <?php $form = ActiveForm::begin(); ?>
            <div class="input-group">
                <?= $form->field($model, 'type')->dropDownList(
                    $unUsedTags,
                    ['prompt' => 'Выберите тип', 'style' => 'width: 270px']
                )->label(false) ?>
                <?= Html::submitButton('Добавить', ['class' => 'btn btn-primary mb-3',])?>
            </div>
            <?php ActiveForm::end(); ?>
        </form>
    </div>
    <?= GridView::widget([
        'dataProvider' => $tagDataProvider,
        'summary' => '',
        'tableOptions' => [
            'class' => 'table table-responsive',
        ],
        'columns' => [
            [
                'attribute' => 'name',
                'label' => 'Название',
                'value' => function (Tag $model) {
                    return Html::a(
                        $model->name,
                        ['index', 'search_query' => $model->name],
                        [
                            'title' => 'View',
                        ]
                    );
                },
                'headerOptions' => ['style' => 'width:90%;'],
                'header' => false,
                'format' => 'raw',
            ],
            [
                'class' => ActionColumn::class,
                'template' => '{delete}',
                'urlCreator' => function ($action, Tag $model, $key, $index, $column) {
                    return Url::toRoute([$action, 'id' => $model->id]);
                }
            ],
        ],
    ]); ?>

TagSearch model:

class TagSearch extends Tag
{
    /**
     * {@inheritdoc}
     */
    public function rules(): array
    {
        return [
            [['id'], 'integer'],
            [['name'], 'safe'],
        ];
    }

    /**
     * {@inheritdoc}
     */
    public function scenarios(): array
    {
        // bypass scenarios() implementation in the parent class
        return Model::scenarios();
    }

    /**
     * Creates data provider instance with search query applied
     *
     * @param array $params
     *
     * @return ActiveDataProvider
     */
    public function search(array $params): ActiveDataProvider
    {
        $query = Tag::find();
        
        $dataProvider = new ActiveDataProvider([
            'query' => $query,
        ]);

        $this->load($params);

        if (!$this->validate()) {
            return $dataProvider;
        }

        // grid filtering conditions
        $query->andFilterWhere([
            'id' => $this->id,
        ]);

        $query->andFilterWhere(['like', 'name', $this->name]);

        return $dataProvider;
    }
}