Magento 2 Custom Module – Implement a Color Picker

As far as my understanding, you are trying to add the whole new Ui component type which call wysiwyg2.

But unfortunately, there is a known issue about adding new Ui Component type (yes, just another one). You can check the original issue overhere.

Let take a look deeper into how Magento 2 dealing with the Ui components in product form.

vendor/magento/module-catalog/Ui/DataProvider/Product/Form/Modifier/Eav.php

/**
 * Add wysiwyg properties
 *
 * @param ProductAttributeInterface $attribute
 * @param array $meta
 * @return array
 */
private function customizeWysiwyg(ProductAttributeInterface $attribute, array $meta)
{
    if (!$attribute->getIsWysiwygEnabled()) {
        return $meta;
    }

    $meta['arguments']['data']['config']['formElement'] = WysiwygElement::NAME;
    $meta['arguments']['data']['config']['wysiwyg'] = true;
    $meta['arguments']['data']['config']['wysiwygConfigData'] = [
        'add_variables' => false,
        'add_widgets' => false,
        'add_directives' => true,
        'use_container' => true,
        'container_class' => 'hor-scroll',
    ];

    return $meta;
}

And inside public function setupAttributeMeta(ProductAttributeInterface $attribute, $groupCode, $sortOrder)

Line 633 (may be different for each version)

        case 'textarea':
            $meta = $this->customizeWysiwyg($attribute, $meta);
            break;

As you can see, customizeWysiwyg() hard-coded formElement to wysiwyg.

If you want to wysiwyg2 working, you need write a plugin for setupAttributeMeta() to add something like $meta = $this->customizeWysiwyg2($attribute, $meta);

But I do not encourage this, you can just create a preference for \Magento\Ui\Component\Form\Element\Wysiwyg, then inside the constructor you can do something like

/**
 * Wysiwyg constructor.
 *
 * @param \Magento\Framework\View\Element\UiComponent\ContextInterface $context
 * @param \Magento\Framework\Data\FormFactory                          $formFactory
 * @param \Magento\Ui\Component\Wysiwyg\ConfigInterface                $wysiwygConfig
 * @param array                                                        $components
 * @param array                                                        $data
 * @param array                                                        $config
 */
public function __construct(
    ContextInterface $context,
    FormFactory $formFactory,
    ConfigInterface $wysiwygConfig,
    array $components = [],
    array $data = [],
    array $config = []
) {
    // Override the component for the WYSIWYG
    // This is not done using definition.xml due to https://github.com/magento/magento2/issues/5647
    $data['config']['component'] = 'Stackoverflow_Toan/js/form/element/wysiwyg';

    // Override the templates to include our KnockoutJS code
    $data['config']['template'] = 'Stackoverflow_Toan/wysiwyg';
    $data['config']['elementTmpl'] = 'Stackoverflow_Toan/wysiwyg';

    parent::__construct($context, $formFactory, $wysiwygConfig, $components, $data, $config);
}

By this way, you can have your own jsComponent, knockout templates..etc and ready to customise to whatever you want.

Hope this helps :)

For adding image field, you can try using plugin and always try to avoid overwrite whole class.

Vendor/Module/etc/adminhtml/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\User\Block\User\Edit\Tab\Main">
        <plugin name="sr_stackexchange_user_form" type="Vendor\Module\Plugin\Block\Adminhtml\User\Edit\Tab\Main" sortOrder="1"/>
    </type>
</config>

Vendor/Module/Plugin/Block/Adminhtml/User/Edit/Tab/Main.php

namespace Vendor\Module\Plugin\Block\Adminhtml\User\Edit\Tab;

class Main
{
    /**
     * Get form HTML
     *
     * @return string
     */
    public function aroundGetFormHtml(
        \Magento\User\Block\User\Edit\Tab\Main $subject,
        \Closure $proceed
    )
    {
        $form = $subject->getForm();
        if (is_object($form)) {
            $fieldset = $form->addFieldset('admin_user_image', ['legend' => __('User Image')]);
            $fieldset->addField(
                'user_image',
                'image',
                [
                    'name' => 'user_image',
                    'label' => __('Image'),
                    'id' => 'user_image',
                    'title' => __('Image'),
                    'required' => false,
                    'note' => 'Allow image type: jpg, jpeg, png'
                ]
            );

            $subject->setForm($form);
        }

        return $proceed();
    }
}

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