SQLite backed with Raid-10 NVME disks and periodic backups to cloud storage is generally more than enough to run majority of the production workloads of startups.

Writes are single threaded, but, you can still easily do thousands per second.

DuckDB offers similar qualities, on the OLAP side.

This is not to say this is best combination.. but, when you consider the simplicity of setup, usage, operations, and backups, and cost element, this indeed offers one of the best, if not the best combination.