I am yet to figure out the economic implications of some countries having a Bitcoin strategic reserve, especially the third world countries as you mentioned. For example, Elsalvado has already key into the Bitcoin strategic reserve, and i think that for a short term, there may be some critical analysis on any likely implications if there is any. However many third world countries may lack the resources to acquire Bitcoin, besides their poor resources, Bitcoin strategic reserve will have a positive impact on the economy of any nation in the future.
In addition, Bitcoin strategic reserve will be an economic advantage of many of these countries if they thoroughly study the gains at the long run. Bitcoin has a limited supply of 21million, meaning there will be strong scarcity in near future, and one of the biggest features of bitcoin that wise leaders should utilize in my opinion.