IIRC, Dokku can only manage 1 server, so it's essentially useless for anything except small side projects that don't need to scale horizontally.
We support Kubernetes and Nomad as deployment platforms, and folks are welcome to build their own builder plugins if they need to support others.
You should run at least 2 servers for redundancy, regardless of size. You just can't lean on a single server, even if you can squeeze thousands of RPS out of it (big doubt).
It will inevitably fail, and you will have downtime.