Is an 8cm thick vertical slit possible in the outer wall?!?

Hello everyone,
in another thread I already asked a few things regarding the renovation of my bathroom.
Now I have another question and hope to get some initial suggestions from you.
We want to convert a room, where oil tanks used to be, into a bathroom. In the corner you see in the photo, there will be a shower. The pipe coming down from the kitchen bothers me a little, and I would like to "hide" it. My plumbing company’s idea is to build a false wall to conceal the pipe. My tiler, on the other hand, thinks that the pipe could be embedded in the wall (pipe diameter 8cm). This is the basement of a prefabricated house (basement built with 30cm masonry walls and the floor above is prefab).
I read that vertical chases should not be made. However, I would find it nicer if one didn’t have to build a false wall but could recess the pipe into the wall. What do you think? Thanks

For a well-founded answer, a structural engineer is needed. For me as a layperson, the slit in width would at least be borderline, as the wall is certainly load-bearing.

Where is the problem with doing drywall on the side where the pipe is, behind which you also enclose the new water pipes? You have to do the drywall anyway, or are the water pipes also supposed to be installed flush with the wall? Drywall is much easier, cheaper, and more flexible.

Apart from that, I wouldn't instinctively remove 1/3 of the wall through the "slot."

Yes, I just wanted to get some suggestions. For example, if someone says that you absolutely cannot do something like that, I don't have to bother a structural engineer any further. But thanks for your assessment anyway.

Where is the problem with doing drywall on the side where the pipe is, behind which you also enclose the new water pipes? You have to do the drywall anyway, or are the water pipes supposed to be laid under the plaster as well? Drywall is much easier, cheaper, and more flexible.

Apart from that, I would intuitively not remove 1/3 of the wall through the "slot".

The bathroom continues like this, so it would be a built-out wall and not just the entire wall done with drywall. The built-out wall would then end after about 150-180cm.

Why shouldn't one be allowed to make vertical slots? Every socket/switch usually has a vertical slot. Vertical is at least better than horizontal. There is a DIN. Something like DIN 1996. Otherwise, just google DIN 1996 slots, you will find something. I personally would have laid the pipe in the wall.