Probably the easiest way to do this would be to have a static TiddlyWiki generated, which includes an RSS feed, and then hook up a tool like Zapier or Micro.blog to read that feed and cross post as needed.
Apart form embedded solutions the export tiddler functionality can be used to export tiddlers in any form you want, so depending on the tools available such as api’s or importing offered by the destination platform you can achieve many things.