Will this work? (getting Alexa announcements when sensor triggers but only if separate ADT system is armed)

We went and had ADT upgrade and activate the old alarm system in our new (to us) house and I know at some point in time that we’ll forget about it and trigger a false alarm, so I’m trying to find ways for SmartThings, Google, and/or Alexa to help with that. The problem is, the ADT system does not work with SmartThings, and while we were told it works with Google, it apparently does not (yet). But I have found that it works with Alexa. I did set up an Alexa routine where some lights turn orange when the ADT is activated, and the Echo Plus announces that the system is armed (and vice versa for disarming). But I would also like to have either the Echo or Google speaker announce a reminder that the alarm is active if someone opens a door with a ST multi-purpose sensor on the door as the trigger. Unfortunately, Alexa apparently doesn’t have the ability to use conditions in its routines (correct me if I’m wrong, I’ve only had it a couple weeks), only triggers. So I can’t have it make that announcement when the door opens only if the ADT is armed.

I’m new to Alexa, but from what I’m finding, Alexa recognizes ST sensors, but I’m not seeing anyway to use buttons in Alexa as a trigger. So I was hoping to use a virtual sensor to accomplish my goals:

Creating a virtual switch and a virtual sensor, then using a routine in Alexa such that arming ADT turns on virtual switch A, disarming turns it off. Then ST uses the status of virtual switch A as a condition in combination with the door sensor to trigger the virtual sensor (when door opens, if switch A is “on”, trigger virtual sensor). Then have an Alexa routine such that when the virtual sensor is triggered, Alexa would say something (“Don’t forget to disarm ADT”).

Can the current version of Alexa recognize a ST virtual sensor? If so, would the above accomplish my goals, or is there a better way to do this I’m missing?

a couple of paper notes attached to the inside of doors will help when the system is armed at home. also, might scare off the bad if they see a note taped to the outside doors that reads “Remember to turn off alarm first!”