Most things people self host are either torrent clients, HTTP(s) or are game servers. The first one can pick a port arbitrarily. The second can do host routing. The third - some of them support SRV records so you can direct the client to an arbitrary port. It’s becoming less common to need multiple public IPv4 addresses.

Nvidia controls enough of the market that more PSU manufacturers would if Nvidia needed it.

The easiest way to think about it is that the conductor is rated for the current, and the insulator is rated for the voltage. Now, once you get into the nitty gritty, they’re more intertwined than that, but it’s close enough for a surface level explanation.

Not gonna happen for me