Just another (alternative) view.
I always like to try and have alternative (back-up) methods of doing things.
Using your phone as a navigation device just seems 'dangerous' to me.
If you fall and land on your phone you could break it,
If you drop it, it could smash the screen on a rock, or fall in a stream
If the batteries go 'flat'...…………….
Not only have you lost your means of navigation but you have also lost your method of calling for help.
When using navigation on my phone I found that it was quite 'heavy' on batteries and I needed to carry a 'battery bank' (recharging unit) if doing full-day hikes.
My own choice is that the phone stays safely wrapped up in the pack and I use a dedicated navigation device, SatMap, Garmin or whatever.
My personal choice is a SatMap as it has a larger screen for 'tired old eyes'.
All quite early days issues to be honest. Personally I have used a smartphone now for at least 15 years. They have evolved wonderfully over the years.
I do carry an old one as backup. I used to carry a spare battery, frankly today the phone is good for a full weekend of GPS work on its battery.
It is rugged and waterproof.. though if it were not I would use a case that is.
I do track every walk I do, though TBH doubt I use actual navigation so much. I either am happy to wander off piste and see where I end up or know where I am anyway.
A few seconds of referring to the Map on the phone is more than enough. I have an image of the map in my head.