There is an even simpler way: contact the members of Vermilion Bird. The Vermilion Bird under the Hongmeng banner is not only responsible for intelligence in the Ancient Realm, but also for scientific research; they should be able to help.
As for finding a Saint to construct a passage, the only person I can think of is Senior Gu Qingyang.
However, he has gone deep into the Ancient Realm, and there is no telling when he will return.
Chapter 396