You can try it at this link : https://bachiramiri.github.io/cosmic-grid/
The purpose of this repos is mainly out of frustration watching tutorials having a static 3x3 grid for their examples.
My approch for square was simple : i mainly focused on the grid css, defining row and columns with a variable, then for the size it was specified in documentation that columns can be defined by % on 'grid-template-columns', that, i get by a dedicated function that returns 100 divided by side size, and the result was not too shabby.
So it can be mainly wrapped to :
Nebular was not the best choice for this case scenario, due to their components having a lot of effects and a ridid min size, a better result could be achieved with vanilla css, but for the purpore of this experimentation it was ok.
Nebular for theming : fairly easy to quick start + eva icon pack
ng5-slider for the sliding effect