Unifi gateways run the management software now, typically they'll also be your networks router and so something you'll need to buy anyway, but if you just want to use the security/wifi elements then you can either run it in a container or if you're really determined not to run a container and not to buy a router there's the CloudKey.

The UDM runs mine, but prior to that I ran a Docker container with it. It worked well.

https://hub.docker.com/r/linuxserver/unifi-controller

Genuine question, if you're running unifi, why don't you want the management vm? Synology makes a decent NAS without the controller.