I was out at the ESRI Dev Summit a few months back. They are building a
pretty useful product called Survey123 (https://survey123.arcgis.com/). It
is written in QT and QML. I believe they are thinking to open sourcing it.
It is build using the XLSform standard.
They added some interesting specs.
I know they would be interested in adding some changes to the standard and
potentially contribute back.
What's the best way for them to proceed, I have CC them so they can chime