Will a range extender work for me

First off I am not real tech savvy and have not yet purchased a range extender. I recently moved to the country where cell service is bad to non-existent. Through research and neighbors' experience I was able to find/install a signal amplifier and get good signal. No one in this area has good signal without an amplifier. My internet is provided through a portable Hotpsot device (model R850) with Sprint. (This setup has provided me with service as good or better than my neighbors and is cheaper and more reliable.) There is no ethernet connection out of the Hotspot. I have a small 1500 square foot house with an attached 900 square foot garage. My exterior walls are metal including wall between house and garage. Wifi service inside the house is excellent. (As good as or better than FIOS which I previously had in town.) My wifi signal in the garage office is only fair at best and sometimes falls out. Question: Will a wifi range extender work for me and if so, what are recommendations for a good extender?  Any help would be greatly appreciated.