I haven’t actually done this, I was just brainstorming. It shouldn’t be too hard of a project, though. The easiest would just be an esp32 chip, limit switch, and small battery and power circuit.

You position the switch were the deadbolt latch hits it in the open or closed position (I’d do open personally). Using esphome with homeassistant would make programming it a breeze.

You’d need to figure out a housing, which is why I wish there was an off the shelf product. I might design one eventually, but it shouldn’t be a huge lift for anyone who is familiar with 3d modeling.