Open shower - how deep?

Hi,

in our bathroom (the developer is currently building the house) a shower is to be installed in a corner.
On the bathroom side (right side, see photo) no partition is planned. That can/should be done by us.

Now there are 2 options:
Either only a glass wall on the right and the shower is open on one side or
Glass wall on the right and a door on the remaining side.

The shower has a floor/wall drain, so without a shower tray.

Question:
How deep/long would the right side have to be so that with a rain shower the bathroom is not flooded?

and second question:
If you have this done by a glazier (Munich area): What is a fair price? According to Google Maps there seem to be thousands of glaziers offering this and I can't ask them all.

ours is 1.20m and it is only minimally wet outside after showering...

Our brick side wall is 1.30m long and the rain shower head is attached to it. It only sprays out minimally; we always place a shower mat or a towel in front of it anyway. I find that with the rain shower head, it sprays significantly less than with a "normal" showerhead, as the water jets aim straight down.

By the way, with an open shower, you flood the bathroom if it is done correctly, since a slope is planned so that the water flows back into the shower instead of out.

An open shower should in my opinion be at least 140 cm, preferably 150 cm deep. I would not go to the glazier, but to the sanitary equipment supplier who offers suitable shower partitions and doors. We have an offer here for a pivot-folding door, 100 cm by 200 cm, real glass, silver shiny fittings, with delivery and installation about 900 euros. With the corner solution, you therefore need roughly 1500 to 2000 euros. It is certainly much cheaper in the hardware store as well. If the glazier offers it cheaper too, let me know.

We once asked an SHK guy who regularly installs bathrooms, and he said that it works without a door from 1.20m. Of course, it depends a bit on how you shower. Retrofitting is still possible, right? If the floor plan allows it. Likewise, you should of course place a towel on the floor behind the 1.20m.

Our glass wall at the floor-to-ceiling shower is one meter wide. Originally, 1.20 m was planned, but then we would no longer be able to easily wheel into the shower with a wheelchair. Still, nothing splashes out and my men are both around 1.90 m tall.