I have Kwickset 910 (I think) deadbolts which support both Zigbee and Zwave (though I mainly use that to monitor the batteries), I’m using them as Zwave as at the time that’s all I had). And the previous owners of this house had an alarm system and when they left all they did was pull the central panel but left the reed and vibration sensors in place.
So I can tell from the reed sensor on the door whether it’s open or closed and from the deadbolt whether it’s locked or not. I even published a list Item widget to combine the two into one widget.
It works great, especially since we use the setting that causes it to automatically lock after 30 seconds. So even if the deadbolt didn’t report it’s locked/unlocked state, I could assume no more than 30 seconds after the door changes state (opened or closed) the deadbolt will become locked.
The deadbolt is ugly to be sure and the fact that each button represents two numbers drastically reduces the actual number of combinations to a pitiful 1024 possible combinations (assuming 4 digit codes) as opposed to the proper 1048576 possible combinations if each number had it’s own button. But there are other better options and we have other mitigations (e.g. the previous owners of our house were also paranoid, each exterior door has two deadbolts, cameras at the doors which will tell us if someone is trying to brute force the lock, etc.).
I’d stay away from the BT ones like August which tend not to be all that secure but both Zwave and Zigbee should be safe enough (you have to consider your personal threat situation though, I live in a relatively safe area of a relatively safe city, YMMV). If you have a smart lock and a contact sensor you can know if the door is both closed and locked.