I carry an Olight 13E EOS on my keychain, and it is in a different league to cell phone flashlights.
It is about the size of an AA battery, lights up a walkway at night enough for a group of people all around you to be appreciative, can be held in the mouth leaving both hands free, and you don't have to worry about dropping it and cracking the screen, using up your cell battery, finding it awkward to use searching under furniture for dropped things, etc,etc,etc.
You can also reach for it and turn it on instinctively with one hand without taking your eyes off whatever it is you are trying to see, or having to stop moving and dig in pockets (my keys are typically hanging on my belt loop).
It's one of those things you couldn't appreciate how often you would be enjoying having until it is available all the time.
Oh, and it is still available if your phone is lost/stolen/broken/dead at night. Pickpockets love phones, they slip out of pockets so smoothly, keys - not so much.