They stopped manufacturing the 5090 even under Jensens control. And no the 5090 die is only 750mm squared big, a B200s die is 1628mm squared. That is more than twice the size of a 5090.
the 6000 pro definitely counts as a server GPU. coreweave seems to think so, anyway
A B200 is two dies glued together. A single Blackwell GPU die is the same size as an RTX 5090 basically.
An RTX 5090 is a reticle sized chip.