Are there any studies/researches on fields like neurolinguistics(or any other fields) to allow people (can be via drugs, psycho training..whatever) to become a native speaker of another language? Is this kind of holy grail?
The term 'native speaker' usually refers to someone who has the language in question as their mother tongue, i.e. it is their first language, acquired as an infant (of course, someone may have multiple mother tongues and so be a native speaker of multiple languages). So under that definition it is not possible to become a 'native speaker' of a language later in life, after acquiring a different language as a mother tongue. However it is possible to reach a native speaker level of fluency in a language which is not one's mother tongue, and this is how the highest level of skill in a language is commonly described in linguistics. So looked at this way it is possible to become a 'native speaker', at least functionally.
Some individuals seem able to acquire a high level of skill in a new language with seeming ease. These individuals are sometimes referred to as 'rapid language learners'. A famous example in the world of linguistics is the late Ken Hale.
If you grow up with two parents who speak different languages, and they both speak their own language to you, then you will start to speak one before you speak the other. However, you will be a native speaker of both languages.
One example is my son, growing up in an English-speaking country. All of his friends speak English, and I myself am a native speaker of English. So he is also a native speaker of English, as much as I myself, or any of his friends. But he gained a degree of proficiency in his mother's language long before he spoke a single sentence of English. So he is the perfect example of someone who had a mother tongue, then became native in something else.
Like you're native language is both of your parent's language. For example, a Bollywood actress named Katrina Kaif was born to a British mother and an Indian Father who was a business man in UK. So her native language is English (since her mother is originally from Britain) and Hindi or any language that her father speaks (since he speaks that language) both languages that her parent spoke and grew up with is her native language.