But you can use inside camera Ivs for push notifications to idmss and record with pixel detection through QNap. This is what I use in similar setups, Ivs is great for less false positive events, but has a disadvantage in continuous recording when an object is inside the detection area. This combination works great for me.
And you are right, it's not possible to record to sdcard and NAS.
That's a good point re using IVS and motion detection. Perhaps my setup has a few advantages.