Add the HTML-widget to your page and to that widget add this script
setInterval(function () {
var x1;
x1 = document.getElementsByClassName('mx-name-TickingTime');
[].forEach.call(x1, function (el) {
el.innerHTML = new Date();
})
}, 1000);
That is what makes the clock tick on https://mydemoversion8-sandbox.mxapps.io/p/home
If you want to call a nanoflow from this javascript, read this post: https://mymendix.blogspot.com/2019/06/how-to-call-nanoflow-from-html.html