How to display a pseudo field in a view
With the help of 4k4, I could solve my problem... I will start by explain my first try, which could be a good solution in some cases, then I will explain/show how I finally end up.

Firstly I created my computed field in hook_entity_base_field_info_alter [Note that this is not a pseudo field this time]

function my_module_entity_base_field_info_alter(&amp;$fields, EntityTypeInterface $entity_type) {
    if ($entity_type-&gt;id() === "node") {
      ...field is created here... will show you how to after
    }
}


Secondly, we need to create a class (that will perform the calculation) for the computed field (will show you after)

Thirdly, we can display this field in a view simply by implementing hook_views_data_alter... This is the beauty of this solution: the view integration is made very quickly. Here is the how the hook is implemented

function my_module_views_data_alter(array &amp;$data) {
  $data['node']['my_computed_field'] = [
    'title' =&gt; t('My computed field'),
    'field' =&gt; [
      'id' =&gt; 'field',
      'default_formatter' =&gt; 'string',
      'field_name' =&gt; 'my_computed_field',
    ],
  ];
}


What was not good in my case, is the fact that my computed field does appears in all bundles (even if I use setTargetBundle('my_bundle') like showed below).

Thus I changed a little bit my computed field process creation:

1-Create the computed field in hook_entity_bundle_field_info_alter ... not in _entity_base_field_info_alter (As you can see, it is a float field... youn could use a string)

function my_module_entity_bundle_field_info_alter(&amp;$fields, EntityTypeInterface $entity_type, $bundle)
{
    if ($entity_type-&gt;id() == 'node' &amp;&amp; $bundle == 'my_bundle' ) {
        $fields['my_computed_field'] = BaseFieldDefinition::create('float')
        -&gt;setName('my_computed_field')
        -&gt;setLabel(t('Nombre de litres total'))
        -&gt;setComputed(TRUE)
        -&gt;setTargetEntityTypeId('node')
        -&gt;setTargetBundle('my_bundle')
        -&gt;setClass('\Drupal\my_module\MyComputedFieldItemList')
        -&gt;setDisplayOptions('view', [
            'type' =&gt; 'float',
            'weight' =&gt; 0,
        ])
        -&gt;setDisplayConfigurable('view', TRUE);
    }

}


Note: if someone know the purpose of -&gt;setTargetBundle('my_bundle') I would be glad to read anything on it as I added it without knowing if it is mandatory/usefull.

2-Extend FieldItemList (MyComputedFieldItemList) [use the same name as in -&gt;setClass('\Drupal\my_module\MyComputedFieldItemList')]

The main point here is the protected function computeValue that will use $node to compute the value.

&lt;?php
namespace Drupal\my_module;

use Drupal\Core\Field\FieldItemList;
use Drupal\Core\TypedData\ComputedItemListTrait;

/**
 * Item list for a computed field that displays the total liter for a soup.
 *
 */
class MyComputedFieldItemList extends FieldItemList
{

    /**
     *
     * {@inheritdoc}
     */
    use ComputedItemListTrait;

    protected function computeValue()
    {
        $node = $this-&gt;getEntity();
        if (! $node-&gt;isNew()) {
            $this-&gt;list[0] = $this-&gt;createItem(0, my_module_function_to_compute($node));
        }
    }
}


At this stage, you have a computed field that you can display in "my_bundle"... Lets go to the view integration

3-Alter hook_views_data_alter to tell views that you have a new computed field linked to a node. The main point here is the id my_computed_field

function my_module_views_data_alter(&amp;$data)
{
    $data['node']['my_computed_field'] = array(
        'title' =&gt; t('My computed result'),
        'group' =&gt; t('Content'),
        'field' =&gt; array(
            'title' =&gt; t('My computed result'),
            'help' =&gt; t('bla bla.'),
            'id' =&gt; 'my_computed_field',
        ),
    );
}


4-Thanks to 4k4, I understood that you need to create a plugin class that will have a render function to show the result in the view. The second important thing here is the @ViewsField("my_computed_field") annotation that needs to be the same as the id in step 3

&lt;?php
/**
 * @file
 * Definition of Drupal\my_module\Plugin\views\field\ComputeField
 */

namespace Drupal\my_module\Plugin\views\field;

use Drupal\views\Plugin\views\field\FieldPluginBase;
use Drupal\views\ResultRow;

/**
 * Field handler to flag the node type.
 *
 * @ingroup views_field_handlers
 *
 * @ViewsField("my_computed_field")
 */
class ComputeField extends FieldPluginBase {

    /**
     * @{inheritdoc}
     */
    public function query() {
        // Leave empty to avoid a query on this field.
    }

    /**
     * @{inheritdoc}
     */
    public function render(ResultRow $values) {
        $node = $values-&gt;_entity;
        if ($node-&gt;bundle() == 'my_bundle') {
            return my_module_function_to_compute($node);
        }
    }
}


Now, everything runs fine:


The field could be displayed (or not) in any display mode and you can change the settings in the UI as any regular field
The field could be inserted in a node view
There is a function my_module_function_to_compute($node) that you can put in your module. This function will compute the result of your field with the entity as argument (node here)


One thing is missing: the sort (in the view) doesn't work... I have to dig into it