Board Thread:Lua Help/@comment-24473195-20140823182718/@comment-4522253-20140824003438

In short: If you can do it with a Template, you can do it with Lua. If you can do it with a Template, but it's really difficult, it's probably easier to do in Lua. If you can't do it with a Template, you are unlikely to be able to do it with Lua.

Use of Lua (at least, as far as Scribunto is concerned) is not intended to replace PHP or JavaScript. Scribunto's version of Lua is not even a programming language in the strictest sense. It doesn't have persistent threads and only produces front-end results, from Wikitext in to HTML or Wikitext out. It can not do backend processing. It's not for applications. It can't parse anything that isn't directly entered to it (even if DynamicPageList is one of your inputs, that's still an Extension that goes through Wikitext processing (unfortunately)). So, I think it's safe to say that unless you find an extension that is willing to preprocess your RSS into a Wikitext variable, it's not going to do RSS processing on its own.

In addition, keep in mind that Wikia's version of Scribunto is a limited backport that is missing some of the basic functions that are commonplace on Wikipedia's Scribunto. It's still in its infancy here. It's good that you're thinking outside the box about the potential, but I think you may be expecting more than it will (perhaps ever) be able to deliver.