It's hard to be sure what would be affected by an EMP... I think the physics say that anything metal that's very thin or very long. Integrated circuits are vulnerable because they are very thin. A Photon Freedom uses ICs to control the LED and provide the dimming, and the LED itself might be vulnerable too. Earlier models might be safer (if they don't have ICs), and it might depend on how intense the pulse was locally.
I believe a standard Altoids tin would provide shielding. I see this as an advantage of metal kits over plastic pouches, and a reason to have a Photon in a tin in addition to whatever other lights you have.
Almost certainly aluminium foil could also provide shielding. If you use a plastic pouch, it might be worth completely wrapping the photon in foil if you care about EMP.
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