Staring at the Sun
So did Trump endanger his eyes by glancing at the Sun during the eclipse? I think that it's unlikely that he was any blinder as a result than he was before, and that his retina's weren't likely to have been damaged. Staring at the Sun is not a good idea in general, but pupillary reflexes normally act to minimize the damage by maximum contraction.
The real hazard occurs during totality, when it becomes very dark in the visible and the pupils open wide. At that point, despite the near absence of visible light, there is still a lot of UV from the corona, and it's entirely possible to stare at the eclipsed circle and get a retina damaging dose.
Since Trump was not on the path of totality, the very bright visible portion of the Sun should have kept his pupils minimally sized and his brief glance was quite likely harmless. I wasn't on the path of totality either, but I put on my eclipse glasses to take a look.
I also made a very crude pinhole camera by punching a hole in a piece of paper with a pen. My favorite view, though, is looking at the shadows of bushes and trees, where accidental small gaps in the foliage make a horde of small pinholes that become transformed into tiny images of a crescent Sun.