Local soda or cordial from Guinea is worth adding because it feels like something you actually noticed while travelling through Guinea, rather than a generic souvenir. For drinks, I would bring a can or bottle for curiosity rather than fill a suitcase with it. I would look for it in a proper local supermarket, covered market, deli, pharmacy, gift shop or small producer rather than leaving it until the departure gate. Back in the UK, it is worth checking specialist shops first because they often stock a better version than a broad marketplace listing. The ideal version is modestly priced, not too bulky, and good enough that you would buy it again even without the holiday memory.