What a bummer. Something like an 80PLUS Platinum ATX PC PSU could do around 40 amps on the 5V rails. Redundant server PSUs seem like an obvious choice here.
if you're using amazon.com/dp/B077R5BVVR/ removing just the outer enclosure and removing that fan should be safe, but it might not be the loudest fan...
otherwise the quietest PC is the one in a different room, but you probably already know that
For USB power? I don't think there should be any way for Pis plugged into the same freestanding hub to talk to each other, but if so you could prevent that with power-only cables.
