Huh, even MySQL and postgres are not apples to apples - we are just now launching a service in MySQL instead of our standard postgres because MySQL has features that postgres doesn't (better connection pooling, potential data partitioning)
For others reading your comment though, I did want to list some things I have used with Postgres that relate to connection pooling and data partitioning:
* PGBouncer for connection pooling/sharing.
* Postgres Table Inheritance for table partitioning (https://www.postgresql.org/docs/12/ddl-inherit.html)
* PGPartman for automating the creation of partitions (https://github.com/pgpartman/pg_partman)
* Citus for low-barrier data sharding (it's a Postgres Extension like PostGIS) (https://www.citusdata.com/)