Some progress, although I haven't tried updating the model from Lisp yet, but to make sure you guys don't dive into it. This works for the model defined in ECL and showing it in a QML ListView:
(defun set-my-model () (eql:qlet ((data (eql:qvariant-from-value *pushover-messages* "QStringList"))) (eql:|setContextProperty| (eql:|rootContext| (qml:qview)) "myModel" data)))
So I was falling into my common trap of running on too many assumptions.
I also called `set-my-model` before `(ini-quick-view (main-qml))` as used in Renaud's template.
The examples help! It's a pity my use-case doesn't fit them 1 on 1.
Regards, Erik