I'd probably bring in my RG280V. It was my first handheld emulator. I had emulated games on my phone in the past and even used a Bluetooth controller but playing on it felt different. More real in a way.
I grew up with the Game Boy so the idea of having thousands of games on the go is pretty neat to me.
I've since moved on to the RG405M.
What about you? Do you have anything neat or special to you that you could talk about for a couple minutes?
If the timing is right, I would bring a mushroom grow bag with mushrooms sprouting.
If not... probably my radiacode gamma spectrometer and some of my radioactive items. Maybe a clock with radium painted dials and a piece of trinitite. I think that there are many different points of discussion that can be of interest to a broad audience (radioactivity, spectroscopy, electronics, US labor law story of the radium girls, nuclear explosions, background radiation.... etc). As a bonus I can bring a UV flash light and show the radium fluorescence. Adults love UV flash lights.
Reminds me of a prank that a physics professor pulled on us. He put the trinitie sample in a large/elaborate Giger counter and then slyly kicked it into test mode while recounting what Trinitite was. “Oh… wait, that’s not supposed to be radioactive…”