ProductPresenter.php

<?php

use Widget\Form;
use Widget\Checkbox;

class ProductPresenter {

    protected $resource;

    public function withProduct($product)
    {
        $this->resource = $product;

        return $this;
    }

    /**
     * @return string
     */
    public function render()
    {
        return $this->renderForm();
    }

    /**
     * @return string
     */
    protected function renderForm()
    {
        $checkbox = new Checkbox();
        $checkbox->setOptions([
            1 => 'Category 1',
            2 => 'Category 2'
        ]);

        // $checkbox->setValue(...)
        
        return (new Form($this->resource))
            ->attributes(['class' => 'product-form'])
            ->action('/product', ['method' => 'post'])
            ->add('name', 'text')           // sub-widget
            ->add('image', 'file')          // sub-widget
            ->add('category', $checkbox)
            ->add('submit', 'submit')
            ->render();
    }

}

FYI @cnsaturn