Zanzito's author(s) can not see your informations, nor are they in any way connected to your device. All the informations Zanzito collects get sent exclusively to the MQTT server of your choice. Be aware of all the possible security and privacy implications: you must be sure that the connection between your device and your MQTT server is secure and that you have properly configured the users that have access to the server and their permissions.
Do not use public MQTT servers unless you know what you're doing: they are “public” so that anyone can see your location and/or you pictures and/or any other information exchanged through Zanzito.
The author(s) of Zanzito does not posses any information about the customer except what is given in the Google Play store payment details. That data will not be used by the author except for accounting and tax purposes, where required by the relevant tax authorities.
Zanzito in itself does not, to the best of the author's knowledge, send any data, anywhere, except to the MQTT server indicated by the user in the preferences. Zanzito has no control over the way Google and your device vendor handle your data while accessing their services, such as Map and location.