I do not see the need for such a necklace.
I (we) live and work for 25 years in the northern Canadian wilderness and do not have/use such gadget.
What I (we) carry is a good Swiss pocketknife, fire-making kit, space blanket, head lamp and vac. pak. pressure bandage.
( items are not 'on person' at most times, just folder, other items in either surveyor vest or day pack, then most possible need for)
Never needed all 5 items at any one time together.
Never used space blaket.
Keep it real, people!