The easiest way is going to be upgrading to APEX 20 where we have the APEX_DATA_EXPORT routine. Then it would be a case of calling the API to unload your data to any form you like, eg

declare
    l_export       apex_data_export.t_export;
    l_region_id    number;
begin
   select region_id into l_region_id
     from apex_application_page_regions
    where application_id = :APP_ID
      and page_id = :APP_PAGE_ID
      and static_id = 'my_region';
    
    l_export := apex_region.export_data (
         p_format       => :P3_FORMAT,
         p_page_id      => :APP_PAGE_ID,
         p_region_id    => l_region_id);
         
    apex_data_export.download( l_export );
end;

Before then, you might be able to get something out of apex_region.open_query_context , eg

declare
       l_context apex_exec.t_context;
   begin
       l_context := apex_region.open_query_context (
                        p_page_id => 1,
                        p_region_id => 2505704029884282,
                        p_component_id => 880629800374638220 );

       apex_json.open_object;
       apex_json.write_context( 'data', l_context );
       apex_json.close_object;
   end;

I think you'll be hand-crafting a *lot* of code.