A:Answer Well, "free" and "PPV" (which means "pay-per-view") are technically a contradiction of terms...but I think I understand what you're saying.
The short answer is "YES", but...you have to find & download the app that will playing the PPV event. Fortunately, Roku has hundreds of apps that are available to download, including some really obscure streaming channels, so if that PPV event is being shown through one of those apps, you should be able to watch it.
If it's on something like a reddit stream, then probably not.