Bitcoin itself is not a magic stick, it can't do nothing if people don't do actual work. I think that the answer to the question how bitcoin and blockchain can help poor countries lies into the governments of these poor countries. They can use the opportunity and create a business friendly environment for Bitcoin and blockchain related businesses by offering companies low to zero tax rates and a high quality personnel inside the country. I think that countries can spend money on educating their talented citizens about Bitcoin and blockchain technologies and make a very good developer out of them.
Creating the right business environment will attract more business to the country which will create more jobs and also increase government revenue through indirect taxes. There were reports that El Salvador has attracted more tourist as well as crypto related businesses since it made Bitcoin a legal tender. With more crypto awareness, young people will find different means to make money from the industry.
El Salvador is a very good example of how can a brutally awful country change very quickly and become a significantly better place. They had a terrible crime rate with a huge portion of violence, that made it terrible place for locals, nothing to talk about tourists. Then, he caught tens of thousands of criminals and started Bitcoin adoption, which played a very good role for country's development. It also significantly benefited country's positive marketing. I've read many posts on Reddit where people were saying that they wanted to travel in El Salvador to experience how it feels to live in a Bitcoin-friendly country.