The technical starting position
A camera can provide live footage via ONVIF while smart detection, audio, settings or PTZ control work differently than in the original ecosystem.
ONVIF can possibly enable basic connectivity, but does not guarantee that every brand function remains identical on another recorder.

A camera can provide live footage via ONVIF while smart detection, audio, settings or PTZ control work differently than in the original ecosystem.
Determine which features on the location are essential and check support in the exact camera and recorder combination. Don't just ask whether an device can be found.
Use a combination that demonstrably provides the necessary features and establish limitations. Choose the same manufacturer when complete functionality preservation is more important than mixing.
Test live image, recording, time, audio, events and any PTZ. Then search for an event in the recorder before the channel is considered delivered.
No. It does not automatically cover every specific function or setting.
Sometimes, but test the features that are crucial for your use.