How to cancel a Piston

Really depends on your device. The physically and programatically features are not present in each device. I also believe that ST took those parameters out of their stock DTH so you might need a custom DTH to expose the features.

For example, my GE Switches will send to ST if the Switch was turned on manually or programatically. However, my GE Dimmers are iffy. This is why the Double Tap App would work with the Switches but not the Dimmers reliably.

In webCoRE, there is a section for these two terms but again, depends on your device.

Simple solution is to just put a button in the room that you can press to trigger a variable in the webCoRE Piston or even a Virtual Switch.

I have also found that using Virtual Switches and a voice assistant such as Alexa works great. Alexa, turn off, XXX automation.

Another thing to think about is good motion sensor placement.

You are definitely on the right track with your thinking, it just that the feature is not widely deployed by all manufacturers.