> lightweight connection; connection bouncers improve the situation, but you still have an unreasonably high memory footprint per concurrent connection.

Pg connections are definitely heavy, but usually on resources other than memory in my experience. If you configure reasonable dirty reclamation and recycling, the memory numbers are often overstated due to Linux tools’ deceptive fork accounting and shared buffers. Ofc, if you’re averaging lots of heavy queries per connection it’ll be truly heavy, but many times the numbers overstate the impact.