Drywall or fabric on a wall of lightweight concrete (siporex)?

[Eaglekotten]

Hello all construction experts!
I am a new owner of a 60s house built in Siporex. The elements are tall and quite narrow, around 40-100cm. My first personal project is to freshen up the laundry room.

Now to the question(s); Gypsum board or wallpaper?

I have been reading on this forum and in older threads that you can glue gypsum boards directly onto lightweight concrete with something like Ardex S48 or PL400. When I read on the manufacturers' sites, and also here, it appears that the wall should be "smooth." Does this mean old plug holes, previous small repairs, and other imperfections must be removed? If so, must they be completely removed or can there be contours of a few millimeters? I am attaching some pictures of how it looks now.

If I'm going to use wallpaper on the wall, I assume I have to fill in the unevenness (some holes with mortar?) and smooth it out with putty. Is this a much simpler solution?

What do those of you who know and perhaps have done similar projects before say?

The main goal is to get a nicer wall and of course, it would be an advantage if it becomes somewhat stiffer (thinking about glue+board) but it's a balance between effort (work and money) and outcome...

Of course, I have also received the advice at the building store to use 12mm plywood with 6mm gypsum on top but I think it feels a bit overkill, but feel free to correct me if I'm wrong

By the way, if anyone has experience with Fibergip, please share it if it could be an option (I have also received this tip...)

All tips and advice are gratefully received!

 

[Willewonka]

Personally, I would have bought a 5L bucket of putty and just fill in all the uneven areas, let it dry, sand, apply more putty if needed, then dry, sand, and finally just paint over with any color or apply a renovation wallpaper. We bought from byggmax and it turned out very well.

If it's going to be a "nice laundry room," I understand that you want new nice walls; otherwise, I don't understand why you would want to spend so much money on drywall.