Reolink sells reasonably priced PoE camera and NVR kits. Check their official store on eBay for deals. Last I checked it was all local, no cloud BS. I’d still isolate it though.

The Mac Mini M4 is unbeatable as a home server imo.

How do you figure that?

Why not use the NAS as a NAS and pick up a cheap SFF or mini workstation for the compute tasks? Only reason I would ever consider running your endpoint as a server 24/7 is cost/availability of just adding a dedicated box.