You're considering what you need to keep tabs on Fido when outside and for every day and can't decide on a hunting device or one of these internet start-ups. It's fairly straight forward in our minds the different between all the options.
Before we get too far, we've written about the tech we use in the past, specifically the Garmin Alpha® 200 i | GPS Dog Tracker, but this device is not something that you'd use on a day-in, day-out basis. Garmin and many other hunting trackers offer a variety of options, in our case, we use the Alpha 200i because we can keep tabs on the dog and it's enabled with the Garmin InReach technology (satellite communicator).
Dog Tracking Devices
You almost need to break these into 'purpose occasion' to better understand the application for monitoring and tracking the dog. While none of us want to be a helicopter parent, a dog is a little different when it comes to ability to know any better and even know where they are. There are probably two types of application:
Daily Tracking/Monitoring: In this case, you need something that has a little more practical application, specifically with the frequency you need to charge the battery and the actual size of said device
Activity/Adventure Monitoring: The availability of the supporting networks to track and keep tabs on Fido. Without cellular coverage, you're relegated to radio frequency and GPS
There are three types of trackers that we would consider applicable to tracking your dog. We use 2 of the 3. Each have their own application and specific to purpose.
Cellular Based Trackers
These are typically smaller devices, need to be charged one every one or two weeks, and use the cellular network towers to triangulate location of Fido. Brands like Whistle GPS Pet Tracker and Activity Monitor for Pets | Whistle Store or GPS Dog Tracker & Activity Monitor | Fi Smart Dog Collar (tryfi.com) fall into this category.
Cellular network dependent - meaning no cell coverage, no dog tracking; however good for everyday tabs on Fido in suburban/urban locations
Requires monthly subscription
Battery typically last longer, for the Whistle product, when the device is near your home and connected to your WiFi network, it goes into low power consumption mode
GPS and Radio Frequency Trackers
The Garmin Alpha® 200i & T 5 Bundle | Dog Tracker & Training typically falls in the bucket of adventure-ready proven technology. Intended for use where cellular coverage is spotty or nonexistent.
NOT good for every day, they are bulky with a big antenna since there is a radio built into the device and battery runs down frequently
Only requires monthly subscription for SOS In-Reach functionality if you pick a device that also has that feature functionality
Primary for hunting and backcountry adventures where your only option to be in communications with Fido will be radio - offer pin-point accuracy using GPS to determine the location of your dog
Typically, water and weatherproof devices, can handle the grueling outdoors
Offers additional features like paging (tone, vibrate, ecollar) and ability to change the light on the device (continuous for low light hikes, it's like a flashlight for the dog)
The lowest in fidelity, this is by far the most cost-effective option, yet least accurate. Since the Airtag requires an Apple device to be in the vicinity of your dog in order to track it, this is not the best option in sparely populated areas like the backcountry
No Apple device in the vicinity of your dog; no tracking of your dog - which is not a major issue in suburban or urban locations
Battery lasts a long time, but these are technically throw away devices once that battery has run out
Not waterproof and requires a case to attach to the collar, not a big issue in the grand scheme of things
So What's Best for Me?
That's a tricky call for you specifically and your needs. We think of it this way:
Everyday: The Whistle
Hiking and Adventures: The Garmin Alpha 200i plus TT15 mini
The Whistle is easy to attach to the collar, doesn't require much charging, and you can setup zones for when you will get notified, add additional family members, and use it as a day-to-day keep tabs on the dog. When it comes to getting outside for more intense off-the-grid adventures, we never leave without the Garmin.
We hope this helps. Get outside and happy hiking!