Dokploy has a web ui with a list of services where you click install and it installs them for you. You can set it up to do the exact same job as OMV but also way less or way more, depending on what you want and need. (by just clicking install on the existing templates, or by entering a custom docker compose if you want to run a nieche service)

So I'd argue dokploy is a perfect substitution (or more like superset) for OMV, but OMV could never substitude dokploy.