Also, whether the reason for the convervative sites readership drop is Facebook cutting news links in general, or views being banned/not promoted from Facebook

Also, whether the reason for the convervative sites readership drop is Facebook cutting news links in general, or views being banned/not promoted from Facebook and co for "fact checking" reasons or plainly for not aligning with the narrative, I don't think the same mechanism wouldn't explain NPR's case. The editor making the criticism wasn't focused specifically on the website, and I doubt it depended as much on Facebook in the first place.