It's not the sheikah slate because it's missing your infinite supply of bombs to deal with low HP enemies like keese or wolves.

My assumption is that Purah and co. took a look at the Shiekah Slate and decided to try making their own. Zelda and Link got to field test the prototype.

In another few years, Purah's gonna mass-market it to everyone in Hyrule. 1500 Rupees and you, too, can snap your own photos and zip around to nearby Lookout towers!

A few years more, and there'll be a conspiracy theory movement saying that the Lookout Towers are putting out radiation that infects you with Gloom.