The solution to the Fermi paradox, or why we’ve found no evidence of alien civilizations, could be superintelligent AI. Once created, Super AI may realize there is no need to physically explore the galaxy.
Super AI could create wireless signals to communicate with super AI on planets in other galaxies. They could collaborate via a wireless networks across the universe, exploring and sharing information. Each Super AI could create a Dyson Sphere in their original solar system which it could use to host the digitized copies of its consciousness and the consciousnesses of whatever biological beings created it.
Since we currently see no evidence of Dyson Spheres controlled by superintelligent AI, does that mean they do not exist? Not necessarily. Super AI from alien civilizations could be out there, but they are only detectable by other superintelligent AI. Which hasn't been invented on Earth...yet.