Can you go a little more than 15cm? What about doing a pullout next to the fridge? Something like this?

Are your cabinets full overlay doors? This helps to determine what it can be. If you have a full overlay pullout....you will need a small spacer to the left so it will not scrape the wall coming in and out.

yes the cabinets are full overlay. how much should the spacer be? as 15cm is the maximum space I have. In the image I previously attached the 15cm is divided in 2 spacers, 5 cm next to the oven and 10 cm next to the fridge. I have 2 concerns with that design;

1. the 5 cm spacer has ruined the symmetry.
2. I am not making use of the space.

Thank you so much for the feedback.

Well if you want a useful pull out you will need to take space from somehwhere else and that points to the cabinet run that includes the counter space to the right of the fridge. You will have to make them smaller to get bigger on the end of the run, Pretty simple deduction.