Key fob died randomly (push start) 🔋

Unlocked the car to get in while out for dinner with my family, and the fob stopped working: car wouldn't start. —Vehicle is 4 months old, fresh off the boat. I cracked the fob open, removed the battery and put it back in, and thankfully it started working again. It got me thinking though, what if the battery completely dies when I'm stranded in the middle of nowhere? Winter would especially suck. Is there any way to start the car without the smart key or am I hooped? Thinking of maybe stashing a spare cr2032 in the trunk.

Also PSA: the fob design isn't awesome. If pulling the fob apart to replace the battery, the spring + silver button for the physical key that needs to be aligned precisely when putting everything back together. I made the mistake of cramming things back together hastily and the key got jammed in the slot. Took some serious prying with a flathead screwdriver to get it back out.

TLDR: fob stopped working while I was out for dinner and now I'm concerned about it happening somewhere inconvenient like a country road