The compute part may be a rack or a cabinet worth of GPUs (though TBH the public designs are currently vague to the point of being artistic impressions), but they also need to come with a PV array big enough to power that, plus a cooling array that's going to be close to 25% as big as the PV array regardless of what unit size they go for in the end.
If they settle on making e.g. 120 kW satellites, that would be about 400 m^2 for the PV and another 100 m^2 for the radiator.
I still cannot believe it's economical to have "data centers in orbit" but I guess the truth will be seen in whether or not it actually happens.
The FCC has regulatory jurisdiction for communications on US objects in space, regardless of distance from earth.
Even very optimistic estimates (by people who aren't Elon Musk) say it will take a decade to get the costs low enough to be worthwhile for LEO; higher orbits are much more expensive.