I tend to always play the cynic in these games. And I think one little way to easily do that is to reverse the roles with an example you are giving. So for your example, imagine somebody from the future came and showed you a pinhead sized device with countless exabytes of computational power projected onto a holographic screen. While I'm sure you'd be impressed and have plenty of questions, I don't think there would be any particular shock. Evolutionary progress - even at absurd scales, is still just evolutionary progress, and easily 'graspable'.
I would agree if we were talking about, say, a team in 1970, but it's worth pointing out that we're talking about a team working during the very infancy of computer engineering (the late 40s/early 50s). Just off the top of my head, you had solid-state hardware, stored-program machines, and the Von Neumann architecture all just popping on to the scene. This is stuff that would definitely have been on their radar, but I think they'd be fascinated to realize how directly and fundamentally those inventions would affect computing.
Perhaps more importantly, I think they would be blown away by how directly and fundamentally computing would change the world. Doug Englebart and his team are the ones who really developed the idea of using computers for something other than performing calculations for scientists. They started that research in the early 60s, and didn't drop the Mother Of All Demos until 1968. So if I were one of the "ENIAC guys", and someone asked me how my work would affect the world, I'd probably just shrug and suggest that the computers I was building would help perform computations that would let other scientists make discoveries more quickly.
1950s was the era of Asimov, Arthur C. Clarke, Heinlein, etc. Give people a spark and we naturally will create a flame, even if only in our minds. Take something current - many people are already envisioning futures where LLMs will not only be running on basically every device, but also integrated into each and every aspect of life. Some even envision them eventually replacing humans in politics, working as caretakers, and more.
It's easy to imagine it - even with absolutely no basis for it whatsoever. Go back millennia to the first men making ships able to embark deep into the oceans, and these people would also have already been envisioning the Titanic. The moment the Wright Bros proved flight viable, many were seeing the Hindenberg. It's just human nature.
That's because you have witnessed the decades of exponential growth. It's not hard to extrapolate that growth further, albeit it still blows my own mind when I see a disk that looks like a RAM, is way faster than my RAM was 15 years ago (2 GB/s? You must've forgotten to take your crazy pills), and has 2000 times more storage.
But show it to a guy working with electromechanical or vacuum tube computers and I'm sure it would be a very otherworldly experience for them.
I'm actually not sure what would blow their mind more - a very big and unimaginably fast computer, or a by today's standards very slow computer that fits on few millimeters. Things like payment cards or SIMs are just incredible too - enough compute power to land on the Moon hidden in a piece of plastic.
Read SF of the era. You probably have some very far futures where the computers running everything are essentially invisible. But SF authors for the most part are not imaging miniaturized supercomputers woven into the fabric of everyday life.
Agreed, I think if you showed me as a kid that a tiny microSD could store every game I ever played and still have room for every TV show I ever watched without getting remotely full, and was affordable, it'd be impressive. But it wouldn't blow my mind as something inconceivable, I had already known floppy disks both shrunk in size and increased in capacity.
Plus, I'd imagine "the ENIAC guys" would quickly realize all the things that were computationally infeasible in their time had more or less been done along the way to modern computers.
