How to get specific page screen ID

Question

I don’t think it’s possible without accessing a global. This seems to work for all pages types, by using the global $_parent_pages with the function get_plugin_page_hookname:

function nackle_get_screen_id( $slug ){
    global $_parent_pages;
    $parent = array_key_exists( $slug, $_parent_pages ) ? $_parent_pages[$slug] : '';
    return get_plugin_page_hookname( $slug, $parent );
}

Usage example:

echo nackle_get_screen_id( 'my-custom-page-key' );

Edit- This can be used on or after admin_init, which is when the menu is parsed and $_parent_pages is populated.