I have installed OWNR wallet app on my iPhone. This wallet offers variable fees, you can set extremely low transaction fee if need it. For example, I payed $0.31 for sending $70 in Bitcoin equivalent. It took approximately 40 minutes to get two confirmations.
I'd recommend to use an open source wallet.
You simply don't know what the application is exactly dong on your device and what kind of information it is gathering.
Additionally, since you can't set the fee manually, you might end up paying a huge fee when the fees spike heavily.
Depending on the calculations, the "low" rate could still be multiple $ if the average fee spikes to a few hundred sat/B. You are better off with using an open source wallet which allows you to choose your fee.