The reason why the “open” strategy works is that, for this particular operating system, the .html file extension is understood as meaning that one should launch a web browser and pass that file to it.   As far as I know, that browser is either going to have to have the address of a file, or a URL to go to.   You can create a local web-server in Perl, opening it with a URL such as localhost::8080, say, but you will have to have (all of) that.   Thus, perhaps in your case “saving it to a randomly-named file” and doing what you’re doing now is a pretty good choice.   I’m just not sure that the alternatives, such as they are, would be in any way worth the bother in this case.