It’s a highway - just not an Interstate-quality one. But it’s better than it was 5 years ago, and IME very likely to be faster than the I-76/PA Turnpike route (as well as having no tolls).
I might change this recommendation if the forecast was for snow.
When yiou say “does not appear to be a highway”, do you mean limited-access Interstate-type highway? Rememberr that Pennsylvania east-west roads tend to cros the Appalachians. I know that one story I read had the narrator’s college-aged kid driving the route, and he used Interstate to the maxdimum extent possible, particularly 99.
The route you got from Google Maps is the one I take (once or twice a year). There are a few stretches on 22 with lower speed limits and some stoplights, but it’s mostly smooth sailing. I average about 2 1/2 hours.