Can I use it without running some inane management VM?

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.

Synology hardware stopped being decent a while ago.

Plus their drive type restrictions which are poison in a cost-sensitive NAS.

(Seemingly rolled back recently, but a roll back can be easily rolled back itself. I don't trust them enough to count on that not happening.)

I like the hardware, cannot stand needing to run another machine just for management.

If you get one of the Cloud devices, you won't need to, as they bring their own.