If creating a dropdown list (select) for the edit() function of a Gutenberg block, registered post types can be retrieved with getPostTypes() via useSelect() in JavaScript. An example of this is the dropdown in the Query Block to select a Post Type.

Below is a simplified example that uses a <SelectControl/> to display a list of all viewable post types, and enables a selected postType to be saved the blocks attributes.

block.json

{
    ...
    "attributes": {
        "postType": {
            "type": "string",
            "default": "post"
        }
    }
}

edit.js

import { useSelect } from '@wordpress/data';
import { store as coreStore } from '@wordpress/core-data';
import { SelectControl } from '@wordpress/components';
import { useBlockProps } from '@wordpress/block-editor';


export default function Edit({ attributes, setAttributes }) {
    // postType defined in block.json
    const { postType } = attributes;

    // useSelect to retrieve all post types
    const postTypes = useSelect(
        (select) => select(coreStore).getPostTypes({ per_page: -1 }), []
    );

    // Options expects [{label: ..., value: ...}]
    var postTypeOptions = !Array.isArray(postTypes) ? postTypes : postTypes
        .filter(
            // Filter out internal WP post types eg: wp_block, wp_navigation, wp_template, wp_template_part..
            postType => postType.viewable == true)
        .map(
            // Format the options for display in the <SelectControl/>
            (postType) => ({
                label: postType.labels.singular_name,
                value: postType.slug, // the value saved as postType in attributes
            })
        );

    return (
        <div {...useBlockProps()}>
            <SelectControl
                label="Select a Post Type"
                value={postType}
                options={postTypeOptions}
                onChange={(value) => setAttributes({ postType: value })}
            />
        </div>
    );
}

The advantage of using JavaScript for the Editor instead of falling back to PHP is you can keep the UI consistent by using Gutenberg controls like <SelectControl/>.

The Settings Sidebar may be a good place to put your <SelectControl/> depending on your goal.

$post_types   = get_post_types( [
       'public'   => true,
        '_builtin' => false,
], 'objects', 'and' );

 <select name="post-types" class="form-control">
    <?php
    foreach ( $post_types as $post_type ) {
        ?>
            <option value="<?php echo esc_attr($post_type->name); ?>">
                <?php echo esc_html($post_type->label) ?>
            </option>
        <?php
    }
    ?>
</select> 

If you want to pass variables ( in this example : CPT ) to block scripts , you can use wp_localize_scripts :

wp_enqueue_script('gutenberg-select-cpt-block', $pathToScript, [], null, 
   true);
wp_localize_script(
  'gutenberg-select-cpt-block',
  YOURJSOBJECT,
  ['post_types' => $post_types] <--- array of data you want to pass
);