Oh, hey! I used Dokku back in the ... I want to say 2012-2013 ? and missed multi-node stuff a bit (nothing that couldn't be scripted around) so this looks cool.
I do see that it shouts 'EXPERIMENTAL!', so I guess it's 'experimental, but official'.
The warning there is more that if the scheduler plugins land in the core (which I hope to do some day), the official usage may change.
For instance, I'd love to abstract our ingress plugin such that it plays nicely with Kubernetes and Nomad (Nomad in particular, since there is no notion of ingress there at all) but that may mean that the ingress controlling functionality in the Kubernetes plugin changes signficantly.
Dokku _also_ has no notion of autoscaling at the moment, though both Kubernetes and Nomad have autoscaling tooling. It would be great to expose this officially somehow vs the plugin-specific method that is exposed in Kubernetes.
Note that at least the Kubernetes plugin is in active usage - even in at least two commercial products being actively sold.