You might start looking into https://www.openhabfoundation.org. I haven't done a deep dive, but they're open source, and claim to be privacy focused, and seem to be trying to be less shitty than the more traditional subscription-style spyware-setups.
It takes some effort but home assistant can work as a full security system. Its also local-only and you control all of your data/sensors/etc. It is very DIY though and you will need to put in the time to not only set it up but to build your own alerts/actions/integrations.
https://www.home-assistant.io/
I also am using Ubiquiti for Security cam's and it can integrate with my home assistant setup as well. I am considering adding in some of their door lock and access card stuff but that's a project for another time.
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