Your function looks correct to me. Is it something you are just postulating here, or did you try it and get some sort of error message or condition?

  (my $pm = $module) =~ s.::./.g;
  $pm .= '.pm';
  eval { require $pm }
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Shouldn't matter if $module is hardcoded or built up from pieces. I actually use this type of idea already in some of my code where the base package is settable in one location, making specifying sub-packages much easier, as well as changing the root-level package.