It is also unique, among those, in being wholly unable to sustain a buoyant aerial unshielded nuclear reactor.

Titan can. But its surface gravity is less than a seventh of Earth's. It seems unlikely people can live on Titan or the Moon for long without fatal loss of skeletal tone. (Mars might be possible, but why bother?)

I forgot to link the page with a big table of planets/moons and their gravities:

https://en.wikipedia.org/wiki/Surface_gravity

Anyways, Mars is an outlier with respect to the "about 1G" crowd, but it's almost identical to Mercury. 0.379g vs 0.377g respectively.

Jupiter is a true outlier at 2.528g.