If you can play from a USB stick then I would get one of these . . . I have one and its pretty compact, mine os on my key ring . . can't say i have ever used it though . . but you never know
https://www.amazon.ca/Kingston-Digital-DataTraveler-DTSE9H-32GBZ/dp/B00B4G2YXA/ref=pd_sim_147_6?_encoding=UTF8&psc=1&refRID=ZH91QDMWQNZ1EYPBXRAF
. . or just get a new phone with bigger storage