I don't bring a rain poncho if I'm going to get wet because of the rain it is what it is
Sadly apps are battery hogs and I've got an old phone..really..the battery gets drained so a charger tends to be a must though Disney's app is always worse than Universal however I think we'll be using Universal's app much more with Epic than we have previously.
You're right about the ID and payment methods, we've had Disney gift cards in recent years for usage for food and merch (though 2017 merch was way better and thus much more bought than 2022 merch).
I will say we did bring small travel umbrellas with us in Tokyo but that is very common to be used there just for shade/heat. We largely didn't use it for that but did have to use it for a passing rain while waiting to get in one morning.
I bring sunscreen because why intentionally get burned? And one application in the morning before you leave the hotel room is not at all enough. But we use a travel sized 3 oz one we just refill from a large bottle. That goes with us on all vacations.
I haven't found
cooling towels to be my thing but I know people use them or small handheld or neck fans to be useful though those also are not my thing.
There's certainly people who bring the kitchen sink but there's still some basic that many people would do well to use, it's not completely a flex to bring nothing especially when you're dealing with the elements