Some ideas that aren’t going to be as common:
Electronics friendly wet wipes - you will get gunk on your tech
Couple ziploc freezer bags - water proof and water resistant are buzz words when the water apocalypse hits and you’re an hour away from shelter
Couple of those moisture sucking packets that come in everything
Bathroom stall and hotel door lock gadget
Golf ball sized portion of Earthquake/Museum putty - doesn’t leave residue and is a sanity lifesaver for uneven cafe tables when you’re trying to work
The lock gadget for bathrooms replaces the inevitable missing lock on a stall so you can go without holding the door closed while sitting there.
For hotel doors, it locks the door from the inside preventing anybody with a key or even brute force with some of models from getting in. A woman I met years ago showed me one she uses and recounted a horror story. I bring one with me now and recommend them to all travellers.