Jupiter pressures would flatten you and me, but not Jovian Witness Piscavians. Just as giant squid, angler fish and the dwellers round black smokers are perfectly happy at abysmal oceanic depths, megaerian life forms will have evolved at their ordinary pressure, and have the same pressure inside and out. Getting to meet them might be a problem, and so would going home to Mummy afterwards. I think we'd be best off developing the space escalator, then parking a giant one next to our target planet, and fishing for samples of the thallatmosphere.