Is around the neck a hard rule? Would have though a chest pouch or hip pack would have been better.

Initial thoughts... and not a complete list.

Whistle
Signal Mirror
Flashing beacon https://www.cejayengineering.com/distress-beacons/outdoor-distress-beacons
BIC lighter https://us.bic.com/en_us/bic-classic-lighters-orange-12-pack.html
Stormproof matches https://www.ucogear.com/firestarting/matches/survival-stormproof-matches-10-pack-in-bag-mt--sv--bulk
Blizzard Survival Bag https://www.blizzardsurvival.com/product-category/bags-blankets/bags/