I got me a Zigbee usb stick for home-assistant and have three different makers of window sensors (Sonoff, Ikea, and Tuya OEM from AliExpress) because of no particular reason. Everything is local, no cloud services. The integration of all has been smooth sailing.
Home Automation
Discussion about general home automation ideas and projects, home automation protocols like Z-wave, Zigbee, Matter, etc, and home automation software and hubs like HomeSeer, Home Assistant, OpenHAB, Homey.
I've got aqara open/close sensors that I use on 3 windows and 2 doors. I like them. I've had them a couple years without needing to replace the batteries but I have some spare coin cells on hand for when I do.
Specifically these ones: https://www.amazon.com/gp/aw/d/B09TP7VMKB?psc=1
They're not a security system in the sense of "can detect a smashed window" but they're great for window open/close automation in my NYC apartment.
Based on your comment and a few others, I ended up buying two packs of these as a starting point and they seem to work well. One sensor lost connection but I was able to fix it and the mesh is more dense now, so it may not happen again. Thanks for the recommendation.
Glad it is working well for you!