Sure but the assumption made already say, that SpaceX uses _all_ capacity for this program (and nothing else) and it doesn't require any double hops (I would think you need to at least add a factor of two for the up/down thing). And that you can see all satellites all the time. So it was a _very_ conservative assumption. And it would still require ~all launch capacity of 2024 and 2025. SpaceX calculations is extremely optimistic to the point of being delusional.

At least without Starship, which I _personally_ think that they will manage to iron out their problems of the course of next year. But even then _this_ timeline they won't be able to keep

They need to do 180 a year to put enough satellites up to even try to hit the 2025 deadline. That's not even counting any satellites which may fail between now and then and need replaced. This is a major reason why the FCC didn't think they could have met the 2025 obligation to reach ~650,000 subscribers with 100/20 and rejected their application.

The calculation above assumes all satellites are available to provide bandwidth to the customers. That means essentially the 260 satellites need to be above the US (let's ignore that the visible horizon is different across the US). Now starlink are LEO, so 260 essentially we need to divide the 260 by the fraction the globe area the US is.

The 260 is a significant underestimate. It's likely 4-10x more