You have Godot wired up to talk to FoundationDB? That's incredibly cool, curious about your use case.
Godot runs using our container runtime on Rivet. The FDB API for containers is currently undocumented. I'd be happy to share early access on Discord – https://rivet.gg/discord
Games running on Rivet usually have a hybrid of actors that handle persistent storage (e.g. a matchmaker) and the game server itself.