If they are in sun synchronous orbit, I assume it would show up as a south-north string near the terminator (sunset / sunrise). Not visible at midnight.
If demand for AI continues to grow 100-1000x fold - there's just no way for datacenters to be sustainably built on earth. Also we already quite close for them to be built cheaper in space.
Fab thing I don't understand tho. Only reason is to bring manufacturing in US since next year China is invading Taiwan so we don't have to defend them.