Good kit, well thought out.

Ideas:

Heating/cooking vessel (as mentioned previously). A 1-2 quart/liter stainless steel pot is always worth having, and you can drink from it directly.

Meds such as aspirin should include an expiry date, since IIRC expired stock can cause problems. Not sure about water purification tabs, but they probably lose potency after x years.

Generic sewing kit?

Deck of cards or two?

Paramedic shears? (People are more familiar/comfortable with scissors for many tasks.)

A couple of roll-up polyester fleece blankets?

A roll of first-aid tape and a roll of electrical tape?

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P.S., Applause for giving time and effort in support of a good charity.