Open Source app to quickly share files between Google Certified and Non-Certified android devices (i.e. Custom Roms)? (Similar to quickshare / nearbyshare, but without Google)

Because Bluetooth is sooooo slow yawn

Edit: And I already tried OTG. Its slow as fuck because of the USB 2.0 bottleneck makes it take 3 hours whereas Quickshare would've taken like, idk maybe 15 minutes or less. Ironically wireless is faster, but I also need it to work for non-certified / custom roms.