re: Libration
Yes, it was possible with Mercury, from the Earth.
As for the Moon, it has librations: it shows a bit of the north pole and a bit of the south pole (not at the same time) and a bit of the east rim and the west rim.
Tjat's because the Moon describes an ellipse around the Earth and has an orbit 5 degrees inclined from the plane of the ecliptic, while Earth's axis is 23 degrees (and minutes) inclined.
In a way, the Moon says "yes" and "no"
Raoul