I'm guessing that real data about exoplanets will be unhelpful because it's hard to detect low-mass planets, and thus answers are likely to be based on the kind of educated-guesswork that we relied on for decades when we really only knew about planets in the solar system.
[Edit]
"No atmosphere"
I'm looking for things like Earth's Moon, or Mars, about which Wikipedia says:
The average surface pressure [of Mars] is only about 610 pascals (0.088 psi) which is less than 1% of the Earth's value.
So, surface pressure no greater than 1% of Earth's atmosphere.