The only realistic way we are going to determine what you posit is
by actually exploring the galaxy with interstellar probes.

Maybe the future telescopes being described that can resolve
continents on Earth-like exoworlds might have some luck in this
area without having to leave the Sol system, but other than
tweaking the Drake Equation some more, I don't see how we
can do more than guess about the varied natures of ETI.

We need to fire up the Daedalus fusion drive, set off the Orion
nuclear bombs, start funnelling up the interstellar hydrogen to
run our Bussard Ramjets, aim the lasers at our giant mylar sails,
collect enough antiprotons from Saturn's rings to power our
antimatter star probes, and explore the Final Frontier!