It should still concern you that no Facebook page rivals these right wing pages. Just because a given URL might break into the top 10 URLs for a day doesn't affect that these pages dominate news feed volume.
If you go to Dan Bongino's Facebook page, you'll see why his page doesn't show up in the by-URL analysis: most of his content is not links to external content, but in-Facebook content. So I'm not sure why it's "misinformation" to point that his page has enormous amounts of traffic, and I think it's misleading to say that it doesn't because grouping by a metric that excludes that traffic.
It seems pretty unfair to argue, "If you just aggregate the data by a dimension that's null for these right wing pages, you'll find they tend to disappear!"
All of the top 10 links shared on FB in a week typically consists of NPR/NYT/TMZ etc. Recently the left leaning website MoveOn was in the top 3 (source: https://twitter.com/tomgara/status/1310314212078620680?s=21).
Shapiro or Bongino are never near the top 10 in terms of link engagement - the metric they do well on is sum total page engagement. Which makes sense - anecdotally, most of me and my left leaning millennial peers are getting our online political engagement from Twitter and Instagram. AOC is a sensation on Insta, Bongino is not.
I see you’re relying on Kevin Roose for your information - unfortunately he’s an absolute spigot of misinformation. I made the same mistake in the past, until I took a deeper look into these issues, and found most of what he says to be totally wrong. I hope you, and others, will reconsider taking him at face value in the future.