A Multi charging cable in one. Iphone, Fire tablet, kindle, apple watch magnet, all on one USB cable. Got it abroad in a shop, but similar are in the usual online places.
Power bank, again I got a super slim flat one that is the same size as the phone and I keep them together with an elastic band. Fully charged of course! That has saved me a few times when flights etc. were delayed.
A fold up backpack that I got in Ale Hop shop for a tenner. Brilliant thing.
Copy of prescriptions, the actual drugs needed in 7 day boxes, and non prescription things I use that I'm never sure I'll get abroad, e.g. fave eye drops, Vick inhalor stick, anaesthetic throat spray, and fizzy paracetemol tabs.
I don't stress about the rest of it. I bring the minimum I need, and will buy anything else at destination.