Regarding Super Heavy Battleships. They were basically a Japanese only specialty. No one else built them. Although other major nations had blueprints for them. They even had plans for a bigger Yamato Class called the A-150. They built the Yamato, the Musashi, and were building a third but mid-construction it was converted into the special Support Carrier Shinano. Which was a hybrid Carrier/Support vessel.

https://en.wikipedia.org/wiki/Yamato-class_battleship

https://en.wikipedia.org/wiki/Japanese_aircraft_carrier_Shinano

https://en.wikipedia.org/wiki/Montana-class_battleship

https://en.wikipedia.org/wiki/Design_A-150_battleship

https://en.wikipedia.org/wiki/H-class_battleship_proposals

https://en.wikipedia.org/wiki/Lion-class_battleship

So I think building Super Heavy Battleships should be very low priority for every nation except Japan.