I prefer lithium primary (non-rechargeable) batteries for devices like flashlights and radios in kits, where that’s reasonable. Make sure that the devices are all the way off, and if you cannot be sure don’t install the batteries. For example, I’ve found that Baofeng batteries in kits that are connected to the transceiver always go flat (and often cannot be restored to service after a few months of that), but that they have very low self-discharge when not connected to the transceiver, even in very warm and very cold conditions.

The kits I built for my no-longer-little Magnets going off to college include a lithium-ion power bank (a model that I have tested for very low self-discharge), a spare 120VAC to USB adapter, a spare 12VDC to USB adapter, and a spare USB phone charging cable. This is in addition to the dedicated charging apparatus for each of their vehicles.

The Sawyer Mini is in my opinion superior to the Lifestraw, other than for size.

I like having more than one two-person Heatsheets, or a two-person Heatsheets along with something else. For example, a contractor bag could be used as a groundsheet and/or part of an improvised shelter, with the Heatsheets being used to stay warm.