Thanks for the links, I did some intensive reading last night - very, very interesting! 
Unfortunately this is not what I’m after. Inspired by the very nice and exceptional work that was done with the YIO remote (seen here), I thought it should be possible to make a low-budget version of it.
Nothing fancy like a specifically written UI (QT QML) or things like that. My idea was, reliable but not expensive parts, that are available to everyone, combined with out-of-the-box working in HA. As simple as possible, using only things, that are widely available and easy to install and use (eg. lovelace cards).
What I didn’t want was something to maintain. Replying and trying to help in a thread is one thing, but maintaining an “app”, nope, not right now and definitely not as a one-man-show… 
The YIO remote 1 was a little over 300.-€/$, that is something that dramatically lowers the WAF… The next generation is even more sexy, but I highly doubt it will be cheaper, as it won’t be a DIY project, it now comes assembled and ready to use… 
Not that I think it would be too much for that exceptional piece of work (art), but it’s too expensive for me and my use case. 
I think it would help, if I could control which lovelace resources are loaded, right now I’m pulling all my lovelace resources, just these JS scripts are killing my user experience with a Pi Zero W. And I don’t need them in that specific view anyway. Funny enough, I see the bottle neck in processing power (which leads me to the scripts), not in RAM consumption…