Translation:The tourist is looking for his passport in the backpack.
Well, here it's marked as inseparable: https://www.usingenglish.com/reference/phrasal-verbs/look.html
And, in general, those phrasal verbs which are separable can only be separated by a direct object, not by an adverbial phrase. Of course, this sentence we are referring to is understandable. And I'm not that kind of expert who could say that it's definitely correct or incorrect. But its structure has changed so much that I don't consider it as a valid translation of the Polish sentence.
Actually my colleague suggested to check the Corpus of Contemporary American English (https://www.english-corpora.org/coca/ - search for "LOOK in * NOUN for") and there are a lot of results, so maybe theory is one thing, and practice is another...
True, the structure is kinda different, but that answer still shows that the learner understood the sentence perfectly, so if I allowed it once, I don't really want to take it back.
Yes, personal belongings often don't need a possessive pronoun, it's generally assumed that they belong to the grammatical subject.
And this has already been discussed thoroughly in this comment section, btw.