I got Dockge running on my hexos machine. This allows me to install arbitrary docker compose projects.
Probably a easy app to get curated. There i already a pull request open for it (on github docs). So if you need to run docker compose today. Use its instal script or try and install via the Truenas UI
hexos or truneas dont run Kubernetes anymore. Natively you got a backend of Docker, VM, or incus LXC.
Truenas just added beta support for incus. You can try there ui to get Kubernetes running?
Otherwise you can get you own Kubernetes running quit easily with something like https://github.com/Esteban-Cruz/K8s-in-incus if you willing to just run a bash script.