Short answer: for a SaaS MVP serving EU and US customers, start with an external uptime check, a small dependency-aware health endpoint, and low-cardinality metrics plus structured logs owned in a region you can verify. Use a self-hosted stack when residency and retention controls are more important than setup time; use a managed service when your team cannot operate storage and alert delivery. The decision is about incident reconstruction, not collecting the largest pile of telemetry. In a l...