Postgres is the materially better (more performant and ergonomic) choice if those are your requirements.

IMO the only place Maria wins is in ease of use / ops.

MariaDB's MEMORY engine has annoying limitations like no variable-length columns, no BLOB/TEXT support, and data loss on restart.

Postgres handles this much better… Unlogged tables skip write-ahead logging so they're fast, but still support all data types, full transactions, and B-tree indexes by default. you can point the data directory at a tmpfs RAM disk and get full in-memory speed with zero feature compromises.