Never leave your Garmin inReach Mini Satellite Communicator behind.
Relatively recently I went hiking overnight with a small group of millennials. The leader eschewed a topo map in favor of her cell phone. I had brought a waterproof topo printout which the leader frowned on as constituting excessive weight. I may be outmoded but my perspective was that millennials are fearless.
I’ve never used GPS and gadgets, but wow!
If he is experienced then why would that not be in his pocket, along with at least a couple of bic lighters and his sheath knife, a little compass, and the basics that outdoor guys carry on themselves even when they would describe themselves and think of themselves as empty handed.
Even my iPhone has a sat linked emergency text option. It’s tough to get lost like that in most of New England. But I would make sure I had some sort of emergency tracker on me if I were out west. It’s BIG out there.
It's why they have clips to attach to your person.