How to install spot ceiling lights in a ceiling without a suspended ceiling?

Oh, the holes and electricity are already installed, so I would look for spotlights with an aperture larger than 100mm, or directly use LED panel lights.

With us, the plasterer reduced the hole with cut-out drywall panels. However, we had a pot in there to which the drywall panels could be screwed.

How was the old ceiling spotlight attached?

There are recessed spotlights that are made for standard on-site concrete boxes (and their dimensions)…

The recessed spotlights with clips should also hold there.

I don't know which technical experts are moderating here. But the idea of gluing was not a joke... Stick the spot overhang to the ceiling with glue, done.