Limestone Floor and Shower - Cleaning Glass in Shower

[VisualThinker7@zzzzzzz]

I assumed that there was some reason the gentleman didn't install a water
softener. That is the most obvious solution, and he didn't mention it.

Let's start with something obvious:
The minerals are only accumulating because water is staying on the glass.
The minerals are dissolved in the water,  the water evaporates off, leaving
minerals behind.

Would it be possible to coat the glass with something clear that will keep
the minerals from sticking, or at least make it easier to clean the deposits
off?

I'm thinking of the treatments we have for glass here in the USA. There's
one for the outside of automobile windshields that keeps water from sticking,
and improves the effectiveness of the windshield wipers. It only has to be
replaced every few months (more often if it rains a lot).
There are others that prevent condensation from forming on the inside of
automobile windows, goggles, etc.
I remember an electric dishwasher soap that  cleaned dishes in such a  way
that no water drops clung to any clear glass stemware or tumblers.  Hence, no
spotting.
Something like this would not permanently prevent the build up, but would
make it much easier to clear the water with a simple squeegee, or just cause the
 water to run off leaving nothing behind.
You could treat the glass once every 10 showers... which in my house  would
be every 4 years (just joking).