Best tablet?

Yes. You can hotspot it to your phone

Tablets are ok, but some tablets don't Gps locate as well as others, which makes for walking around quite the mystery when trying to follow along. An old phone that no longer has a service provider is really a great option. Hotspot wifi for an old (not too old, iPhone 5s are now too old) phone and you are good to go.
Plus tablets are a big and heavy for a little one to walk around with for a long period of time.

I use an iPad hooked up to my IPhones hotspot don’t have any problems

Why was it that she can’t have a phone? Even if you get an iPhone without activating it she could still text people and download apps when WiFi connected

Make sure that your phone plan allows to hotspot and track how much data is included. I have AT&T in the USA and there is an additional monthly charge on my plan for this. My wife has a local carrier and there is no charge from her phone. Since each carrier has dozens of plans there is no way anyone on this board can answer the question for you with certainty.