Vinyl in floor-level shower

The wordplay through your username , who does not want (or should not want) to lay tiles (Stone), pleases me. I align myself with the opinions already expressed and see no sense at all in installing lower quality for more money and effort. I do not like such products anyway but prefer either stone or wood or....., never stone in wood look or similar. I understand the basic idea of having an even floor laid, but then both the rooms and the budget should fit, because this type of flooring often causes quite significant problems if the installation is not really optimal. It also seems to have something to do with current trends, which are usually short-lived, and I would therefore always choose rather classic solutions. As my tiler already said, the formats are currently getting bigger (and more expensive) before they get smaller again; all that has happened before. Even with tiles, I see no compelling reason for a particularly expensive format, unless the two aforementioned circumstances (conscious overall design & budget) are present.

are the formats currently getting bigger (and more expensive)

Bigger yes, but the large formats are now "dirt cheap". You can get 60x120cm from 29-39€/sqm. A few years ago, this was unthinkable.

Bigger yes, but the large formats are now "dirt cheap". You can get 60x120cm starting at €29-39 per sqm. A few years ago, this was unthinkable.

Okay, I see that I am no longer completely up to date on this. By now, there are certainly new trends, which are usually admired right at the entrance.

She just imagines wanting to have a uniform floor in almost the entire house.

She partly has a good "imagination" about that. On one level, for example on the ground floor, where the doors may remain open or are not even present, it is a method to achieve spaciousness through consistency. But that definitely does not apply to different levels as well as different functions. For example, a technical room or utility room can be excluded from this if the door is kept closed anyway. A house can also "grow" through a completely differently designed WC room or a room with another function. The same applies to a bathroom. Some are just a bit less imaginative (not meant disparagingly) and prefer it consistent, also because they are not willing to perform so much creative mental gymnastics. One is simply more creative, the other more pragmatic. Whether you want to install plastic in your house is another thought. Vinyl (PVC) seems to have replaced laminate, while one can say that laminate back then replaced the PVC floor.

But I didn't expect that this wish would be quite special.

Well, would you lay laminate in the shower? The idea is basically the same.

Admittedly, a vinyl floor feels more pleasant than tiles.

Nowadays most build with underfloor heating. Honestly, you don't have to pay attention to "warm surfaces" now. Tiles also have their positive sides. Personally, I avoid all these pirouettes when it comes to warmth/cold, heating/cooling, etc. For me, tiles are still the be-all and end-all in a bathroom. Of course, the entire level does not have to be designed as a wellness oasis like the bathroom ;)

Drive to Denmark, it is quite normal there for the bathrooms to be completely covered with vinyl. They also have American toilets and no tile backsplashes. There are certainly companies in Germany that can do that. It just has to be cut and grouted cleanly.