That is what the “regular” PlanetScale is all about. It uses the Vitess open source project to do write scaling through shading. It is very powerful and customizable and stable. It was built to run YouTube. Former happy user here.

Vitess/Planetscale? Neki is essentially a version of Vitess for Postgres fom the same guys.

TiDB: Distributed and MySQL compatible

MariaDB Galera or Vitess.