You can get by much cheaper as well - e.g. occasionally I use TP-Link Tapo cameras which record to internal SD card and can also stream to Synology NAS Surveill

You can get by much cheaper as well - e.g. occasionally I use TP-Link Tapo cameras which record to internal SD card and can also stream to Synology NAS Surveillance Station software (all local). I'm a bit miffed that the app is trying to sell cloud storage, but for now a full cheap local setup is still possible. (For a serious setup I'd of course opt for something more serious).