From everything you have said, I have no doubt about your intelligence. Being able to communicate this clearly in a second language is an impressive and employa

From everything you have said, I have no doubt about your intelligence. Being able to communicate this clearly in a second language is an impressive and employable skill on its own. Combinatorics and algorithms are specific skills that you need some experience of (nobody has an innate talent for these, without learning them), and some coaching would be useful here if you haven't had formal education in them. But - if you like making physical stuff, then maybe data science is not your passion? Your projects sound impressive but don't seem directly relevant to what you are applying for. If you have projects, but none that are relevant, this may open questions about your suitability for the field. I feel that these might be more valued in another field, such as robotics?