So what kinds of cool stuff could be built with a room temperature superconductor? Better levitating trains?
They won't replace portable batteries soon, but room temperature superconducting will greatly increase efficiency in all areas of electricity, including higher power motors (the efficiency gains are good enough that superconducting motors and generators have been attempted despite needing supercooling). Also, a simple SMES could easily buffer future BEV truck charging station despite projected 1MW connection per charging truck.
Why do you think any of these are true?
"Who knows what could come out of that? Robust high-current-density room-temperature superconductors are right out of science fiction (SF readers will recall that one such material was a big plot point in Larry Niven’s Ringworld). Electrical generation and transmission, antennas, power storage, magnet applications (including things like fusion power plants), electric motors and basically everything that runs on electricity would be affected. We could stop throwing away so much generated power on heating up the wires that deliver it, for starters."
What matters is how lead is handled. With hope, mankind will never lead a generation the way burning millions of gallons of leaded fuel did. Certainly no use of a lead superconductor could hope to accomplish that level of damage.