Depends on the context of essential.  Essential for survival, no. Essential to have a good time, probably not. 

I have the Garmin 6S Fenix ProSolar, I wear it everyday. I love it. I take it everywhere. Can I go without it, yes. Do I want to leave it at home, heck no. But I use it to track way points, keep me on track for the day depending on how much I have to hike, I’m also a female and it tracks all those pesky female things. It is a great fitness monitor, it has all sorts of fun gadgets to use, and it’s water proof. 

Superusers do not speak on behalf of REI and may have received
one or more gifts or other benefits from the co-op.