What's the highest pressure that can be achieved over a useful (1 meter?) distance? I find it amazing that they managed to scale up cryostats to 1km for superco

What's the highest pressure that can be achieved over a useful (1 meter?) distance? I find it amazing that they managed to scale up cryostats to 1km for superconducting powercables at low temperatures - it would just be interesting if they started scaling up high pressure environments.