i'm using recalbox on an Odroid XU4 and i want to know if it's possible using 4 PS3 Controllers on 1 Bluetooth dongle at same time and if so, which one i should get?
yes you can.
one compatible with linux.
not always easy to know if that's compatible.
i think that most of them work, while only 1 of my bluetooth dongle doesn't work on linux (among 5)