Buddy 101paweł - I do not see the glazed edge or the tile there, this is a porcelain tile, cut to a plinth at the factory or at the construction site, the edge looks original, so either two plinths from one tile, or cut with a water machine.
As for the finish of this space, it can be done as you suggest, but:
- What about the piece of grout visible from above?
- I would not put silicone in this place, it cannot be painted.
PS When laying silicone - either you use painter's tape on both surfaces, without spraying with liquid water - or you use liquid water, no tape.
It is not about slippage, greasy places around the arranged silicone prevent it from sticking there, it only stays where it was placed before spraying it with a greasy liquid (water with dishwashing liquid works best).
You can even use a teaspoon for pulling, it's a matter of the width of the silicone thread you want to arrange. If it is to be tiny, use a small ice cream stick, if you want a larger one, take a teaspoon.