For Firebase-based mobile applications in which latencies of ~1 minute (or manual sync) are acceptable, will power consumption be optimal? Is it possible and does it make sense to adjust keep-alives, etc?
Firebase is optimized for real-time communication (meaning as low latency as possible). While I have no reason to suspect it'll be a power hog, we haven't (yet) optimized for power consumption or done any in-depth testing.
Feel free to email support@firebase.com if you do any testing on your own and want to share your findings.