we are looking for a best practice solution: How to create a backup of the interview data on a second device. The aim is to reduce the risk of data loss when the original device is stolen or breaks down. We have enumerator teams working with Android smartphones in remote areas for about one week without internet (server access).
The idea is something like an easy copy app (full or incremental) from enumerator device e.g. to supervisor device, on daily basis.
You may be interested in reading a very good writeup by one of the ODK folks regarding using a Raspberry Pi (ie low cost, low power, portable Linux box) as an interim backup device for remote offline field work. Such a setup may be adaptable to your needs. See https://forum.opendatakit.org/t/raspberry-pi-odk-briefcase-based-hub-server-for-offline-online-management/15501
Interesting, but we are looking for a less “technical” version, and we have several remote teams in different locations (>> about 5 Raspberry Pis), with few IT know-how. Just something, like copy KoBo data folders to device of a team-supervisor (smartphone as WiFi-hotspot).