And all the dragless satellites around the earth are focusing on documenting as all the frictionless spherical cows on the earth

Are any of them truly free of drag? Like, are there 0 molecules of atmosphere at some height, or just entirely negligible amounts of atmosphere for all practical purposes?

None. In theory there are parts of space that are a true vacuum but not everywhere, and definitely not near planetary bodies.

There's a reason our satellites need station-keeping fuel. https://en.wikipedia.org/wiki/Orbital_station-keeping

Even in deep space there are something like two atoms per cubic meter just "there". But atmospheric density drops exponentially with altitude.

Yeah anything above about ~1000km or so is essentially zero drag.

It adds up. Also, Kessler syndrome potential is not negligible.

Kessler syndrome is important but somewhat unrelated.

Beyond LEO the drag is really negligible in the sense that other factors (e.g. gravitational abnormalities, the moon) have larger effects.

IANAP ("I am not a physicist"), but any two objects in orbit around their common center of gravity are slowly radiating energy into space in the form of gravity waves. This is why LIGO reports its chirps. Of course, this isn't very much energy, but given enough time all should orbits collapse.

I am a physicist. The gravitational energy loss from planet + satellite scale orbiting bodies is so small as to be orders of magnitude less than, say, the influence of gravitational anomalies like the Himalayas, or the tidal pull of the Moon.