Jonathan from the Institute for Human Anatomy and a willing cadaver demonstrate the path of a nasopharyngeal swab during COVID-19 testing. Spoiler: Bone protects your brain from the probe but the distance the swab goes into your head is, Jonathan says, "pretty remarkable."
That said, my 11-year-old daughter was tested (fortunately, negative) and she said "it was uncomfortable for a second but not that big of a deal."