I cloud imagine taking the RSS feed and making a static copy, actually two copies (lets call them AcmeNews.rsd and AcmeOpinions.rss). Then, using a (xml) text editor, I would delete all the news episodes from the opinion feed and all the opinion episodes from the news feed. Store the files on a web server. Test them, e.g. with a podcatcher.
Do you want to keep the subscribers ? If so, to which feed shall they be send?
Set-up two new Podcasts for AcmeNews and AcmeOpinions, let's say you stick with PowerPress (and a (self-) host behind it). Then you go to the dashboard and select “Import Podcast.” here you give the link to the edited, static, RSS files on a web server. The PowerPress will import, based on the RSS feed, and you have a new podcast with all the selected content.
Depending on where you want to send your old subscriber base you put this RSS feed as target (either AcmeNews or AcmeOpinions) for the 301 redirect of your old, combined podcast RSS feed.
Unfortunately you can not redirect simultaneously to both new RSS feeds, only one target is possible afaik.
This should work. I would suggest that you use a good XML editor to clean up the RSS feed (maybe the trail version of Altova XML Spy will do it, Visual studio code (plus an extension) or you write a script).
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