TL;DR A cluster of discarded smartphones can match the cost and performance profile of cloud server instances for a defined, bounded class of workloads bursty, latency-tolerant, horizontally-scalable services like microservices, dev environments, and educational platforms. This isn't a sustainability thought experiment. A 2023 prototype (10 Pixel 3A phones) ran real end-to-end microservice benchmarks at roughly 1/40th the three-year cost of an equivalent AWS instance. A 2024 follow-up deploy...