What can be used to level the concrete stairs?

I have two left hands for something like that. But fortunately, our current neighbor is a self-employed floor installer and does this at a very fair price.

But he doesn't want to do the height adjustment?

Regarding the material question, I wouldn't care at all. The few bags of screed are available for 50€ at the hardware store. The work is the problem.

Use fast screed, material costs about 150 euros. Formwork is elaborate, but you can do it yourself quite well. I estimate working time about 3 days for one person. Should not cost more than 1200 euros.

I am only concerned with which is the optimal solution:
[Screed] or [Sand & Standfeste Spachtelmasse]

I only know the first solution, never seen or heard of the second one