A handheld computing device has an operating system (OS), and can run mobile apps. In the 2010s, most handheld devices are also equipped with Wi-Fi, Bluetooth, near field communication (NFC) capabilities and Global Positioning System (GPS) capabilities.
Skyscanner allows you to find the cheapest flights to Phoenix-Mesa Gateway (from hundreds of airlines including American Airlines, Delta, United) without having to enter specific dates or even destinations, making it the best place to find cheap flights for your trip.
PHX Mesa Gateway airport is a good half hour away from Sky Harbor. Car rental availability there is more limited and transportation to other off site rental desks in PHX will be costly. That is just a fact and a consequence of flying into Mesa.