> I believe another contributor managed to get an app running using Postgres, but I don't know how they did it. I think there's some aspect of the Sandstorm sandbox that throws Postgres for a loop, and you have to kinda hack around it.

That would be me. I've done it on a private app and helped bring it to another app, so it's repeatable. I'll try to explain it on the sandstorm-dev group in the next week or so.