You can use Javawa RTWTool, that you can download from: https://www.javawa.nl/rtwtool_en.html (See also: https://www.zumouserforums.co.uk/viewtopic.php?t=2376)

Note: You open a KMZ/KML file directly in that tool, you dont need to convert it to GPX first with gpsvisualizer.
See the screenshot how ...

Thank you! Yes as I mentioned in my post I'm aware that other methods exist. But as you said they require a bit of learning meanwhile almost everybody is familiar with the Google UI and the ways of navigating with Google Maps.

Appreciate your feedback! I hope someone will find my experience ...

I found a not-so-hard way of taking a route I created on Google Maps to my Zumo XT and just wanted to share with potential fellow travelers struggling to find a solution that just works.

First a bit introduction: For good or bad I am from the "lucky" young people that grow up with technology. I ...