I wonder how terrible would it be to use DuckDB as the main database (running transactions) for a small project?
The DuckDB devs measured it ~30x faster than PostgreSQL (and ~3x faster than Arrow Flight) for bulk transfer, which pg is known to be very slow at, and a bit faster (<2x) than pg for small writes up to 8 threads, after which they say that pg continues to scale well with number of threads but DuckDB plateaus.