wait, how do we know that Keith had firsthand experience with the galra (other than the whole parent thing) before the series began?
Well, I just covered that- in s1e1 he stops looking for the Red Lion and stares at Zarkon’s stylized X-crest on Sendak’s ship in a way that suggest he absolutely recognizes that- but presumably, from a long time ago, so that he can know immediately he’s seen that symbol before, but not place where he’s seen it or under what context.
Other details, though:
Keith’s red hoverbike from the first episode is structured incredibly similar to the smaller craft that we see deployed by the Lions in the Balmera rescue mission. Its aesthetics are basically completely unlike any other piece of earth technology, and the presence of schematics on the wall of his desert shack would suggest that he built it himself. Hover technology like that is fairly common with alien technology that we’ve seen but Keith’s bike is the only thing that has it that we see on Earth.
Pidge, who’s not only technically minded but has a very solid grasp on theory and proper terminology, calls the bike a “thing” in a tone that clearly suggests she has no idea what it is and hasn’t seen anything like it before. (“Is this thing big enough for all of us?”)
The rest of the team also doesn’t seem to understand its capabilities the way Keith does- Keith knows the bike can go off a cliff, even heavily encumbered, and catch itself without crashing, but the rest of the team panics, at which Keith is basically just exasperated (“Shut up and trust me!”)