Perinci::Object::EnvResultMulti3pm

 use Perinci::Object::EnvResultMulti;
 use Data::Dump; # for dd()
 sub myfunc {
     ...
     # if unspecified, the default status will be [200, "Success/no items"]
     my $envres = Perinci::Object::EnvResultMulti->new;
     # then you can add result for each item
     $envres->add_result(200, "OK", {item_id=>1});
     $envres->add_result(202, "OK", {item_id=>2, note=>"blah"});
     $envres->add_result(404, "Not found", {item_id=>3});
     ...
     # if you add a success status, the overall status will still be 200
     # if you add a non-success staus, the overall status will be 207, or
     # the non-success status (if no success has been added)
     # finally, return the result
     return $envres->as_struct;
     # the result from the above will be: [207, "Partial success", undef,
     # {results => [
     #     {success=>200, message=>"OK", item_id=>1},
     #     {success=>201, message=>"OK", item_id=>2, note=>"blah"},
     #     {success=>404, message=>"Not found", item_id=>3},
     # ]}]
 } # myfunc

To add a payload for each result:

 my $envres = Perinci::Object::EnvResultMulti->new;
 $envres->add_result(200, "OK", {item_id=>1, payload=>"a"});
 $envres->add_result(200, "OK", {item_id=>2, payload=>"b"});
 $envres->add_result(200, "OK", {item_id=>3, payload=>"c"});
 return $envres->as_struct;
 # => [200, "All success", ["a","b","c"], ...]