Oh yes the old argument "just use your phone.. it has GPS.. it is much better". short answer it is not.
A dedicated GPS device does what it is designed to do VERY well. Points of interest, next gas stop in X miles, navigating around small and large towns equally well, dedicated maps, "offline" support, editing way points and uploading them, better battery power.
Last summer I did 5000 miles in two weeks I have a pretty good idea what works and what doesn't. I used both Garmin something (car model) and a Samsung S8 + Waze
Garmin
1) simple 1 button operation for most functions
2) larger screen; easier to read in dark/light
4) better navigation when the mobile phone loses data connection (route planning when you change your mind) [dont tell me some BS about "oh just download the whole state of Texas to your phone before you leave..."
5) simply better for long trips (7+ hours in the saddle)
6) Quicker finding stuff (though in fairness sometimes that stuff didn't always still exist; my fault for not updating the maps [looking at you random gas station in western Texas]).
7) A bit bulky on the handle bars; nothing too crazy.. what do you do with it when you leave the bike? Leave it mounted / take it off and stash it?
8) my Garmin model also has the traffic feature; it works "ok"
9) durable; I've dropped mine several times it bounces off the ground without any special protection just fine.
10) water resistant enough to be mounted on the handle bars and ride at 35+ mph no problems with operation.
CHEAP! Buying a used GPS at your local pawn shop is the way to go! Craig's list is another gem. Note: when buying used make sure the unit has been map updated in the last 18 months (preferably in the last 12 months). Garmin will flag a serial dormant / end of life if it hasn't received map updates "regularly".
I do have 2 of the same model because I bought them used and their were cheap!
I am using a Garmin Nuvi 65LMT
https://buy.garmin.com/en-US/US/p/147609
Mobile phone
1) around town trips it is better (waze traffic)
2) a bit less hassle to mount up and use
3) one less item on the handle bars (i'll just navigate via sound)
4) more real time / accurate information for places of business
5) more portable
6) you can dunk a Samsung S8 so rain isn't a problem
7) wireless charging works good and you will need it because GPS operation EATS your battery usage
In the end use the right tool for the right reason.