Found no way to adapt the DW1 to my garage door as the magnet kept getting ripped off. Most commercial garage door sensors use a mercury tilt bulb. I purchased one and removed the NC magnetic reed switch from the DW1 and soldered in the tilt bulb. Double stick tape to the garage door. No companion magnet needed. Works perfectly.
Simple fix. 10 bulbs from China for $1.10
Lets call it the DW2 with jumper header to select magnetic reed or tilt bulb...... and maybe two hookup terminals to send a contact closure as well.
Good idea and nice workaround !
Building on your idea, would recommend a general purpose connector. There are no other Sonoff devices with dry contact sensors, this could easily fill that gap too !