

You don’t need an NVR. The camera supports a microSD card to store footage. It also supports FTP upload.
HomeAssistant isn’t required. It is supported and I do have it configured.
I have next to no recollection of how UniFi works so I can’t speak to that. Mine is connected to a 2.4GHz WiFi network. IIRC that’s all it supports. Might be different with newer models.
It also supports HTTP(S)/RTMP/RTSP/ONVIF streaming. Though I tend to just use the app (and I’m particular about installing apps) as I find it quite usable.

TL;DR: I don’t daily drive (Free)BSD because it doesn’t work with some hardware and software that I use.
I’m not an expert in the BSD’s. But I’ve tried to daily drive FreeBSD a couple of times and can speak to it for myself from that viewpoint. Most recent attempt was about a year ago.
The issues I had:
Poor WiFi support. I understand that wireless driver support is iffy and even if it does work, it has poor speeds. I tried this on my laptop and could not get WiFi to work. There was a workaround in passing wireless card through to an alpine Linux guest VM and connecting there then creating a bridge. I did get this to work, but I found it impractical.
Games (via Wine/Proton) aren’t really an option. I understand you can install steam via a Linux compatibility layer and it’s somewhat functional with workarounds. I did not try this.
Those were dealbreakers for me. But the desktop experience itself was good. I ran KDE, and it felt the same to me. if I was running it on a wired machine that wasn’t used for gaming, I think I’d be happy to use it.