Former DOD folks who expound on this matter have been dismissing the idea that these beings (whatever they are) have traveled across the vastness of space.
There's even been a lot of talk that they've been here (on earth, in our reality) all along.
I always think about the seismological tests we did on the moon. When we crashed a craft into the moon it literally “rang” for hours. Hollow?
Even more advanced would be interdimensional beings who mastered traveling in the multiverse that string theory tries to explain. That feat would make FTL travel seem like horse and buggy stuff. Or given earth is 4+ billion years old a prior advanced civilization could have evolved and left earth only to return millions of years later. The ice moons of Jupiter and Saturn offer resources for deep space living. Mars does as well. Venus in the clouds at the right altitude has a zone with pressure and temps that are nearly identical to earth if you don’t mind sulfuric acid rains and nearly pure CO2 “air” it is thought that humans someday may have floating outposts in the Venus clouds at those levels. Using methane as lift gas or even 80%N2 20%O2 as lift gas you know air.
This has long been my belief. In fact, I'm thinking it is a species derived from the octopus, which is itself a most amazing creature.
Yeah, like Pelosi...and Schiff.