you forgot
IoT
Investors want otherwise.
The software that the synology uses on the backend is open source, so you could set this all up with proxmox or a debian server or something, too.
you need to ensure your cameras support either direct access inside the network, or onvif or something like that. IDK, i don't use it anymore, but i did for a good long while, with wifi and wired IP cameras. My synology had a "license" for 12 cameras, but lightning took it out (something about a bunch of ethernet cables in trees), and my new synology doesn't have enough licenses to bother with.
anyhow, just thought you should know - "software" "NVR" is available, and has been for over a decade.
I think IoT was more than just hype.