I carry "entertainment hardware" in my day bag. A PaperWhite3 eBook reader, Kindle Fire HD8 tablet, and small Sansa MP3 player. Along with all kinds of ways to charge them (and my cellphone too): 15,000mah power bank, cigarette lighter plug in, wall plug in, USB-C cable, micro-USB cable, mini-USB cable, and (not for charging) an OTG data connection cable.

Oh, one other thing that I suppose is actually more "unique" - an AliveCor KardiaMobile heart monitor. https://www.alivecor.com/

I bought this gadget when I started having heart arrhythmias. Being an ex-Paramedic, I wanted to see what was happening. I use it on others as often as myself these days. Just yesterday I looked at the ECG for an elderly friend who was not feeling well.