As per title, any suggestions?

Basically: I'm looking for a sensor that can tell me whether the deadbolt of a traditional lock is correctly locked or not. By locked, I mean out and in the opening in the frame.

Most smart locks I found tell me whether the deadbolt is in or out, but if the door is wide open and the deadbolt is out, they'll still mark it as locked.

I found a mechanical switch that replaces the strike plate and bolt hole in the door frame so if the deadbolt is correctly in it, the circuit is open. But it's more than 100$, and it looks like they're out of stock.

I was thinking of building something with a simple magnetic sensor, but I fear aligning it properly with the bolt and keeping it running over the years will be hard.

The doors are wired, they had an old alarm system and wires are still good, it would be easy to get them in position.

Any idea or suggestions welcome thank you!