Checking if an item is visible in PL/SQL

This example might help

declare
  l_exists boolean := false;
begin

  for c1 in(
    select
      aapi.build_option_id
      ,aapi.condition_type_code
      ,aapi.condition_expression1
      ,aapi.condition_expression2
      ,aapi.authorization_scheme_id
    from apex_application_page_items aapi
    where 1 = 1
    and aapi.application_id = :APP_ID
    and aapi.page_id = :APP_PAGE_ID
    and aapi.item_name = 'PX_MY_ITEM'
  ) loop
    l_exists :=
      apex_plugin_util.is_component_used(
        p_build_option_id           => c1.build_option_id
        ,p_condition_type           => c1.condition_type_code
        ,p_condition_expression1    => c1.condition_expression1
        ,p_condition_expression2    => c1.condition_expression2
        ,p_authorization_scheme_id  => c1.authorization_scheme_id
      )
    ;
  end loop;

  if l_exists
  then
    htp.p('item exists');
  else
    htp.p('does not exist');
  end if;

end;