Short answer: No, not yet.
Long answer: No, probably never will be. The way the external SD is loaded is emulated. No hard coded(so to speak) hopefully that makes sense to you.
Sent from my LG-E980 using XDA Premium 4 mobile app
Future Phone: LG Google Nexus 5
Current Phones: Samsung Galaxy Note 3 AT&T[Rooted], LG Optimus G Pro AT&T[Liquid Smooth]
Past: LG Optimus G AT&T, LG Google Nexus 4, Samsung Galaxy S3 AT&T, Samsung GS2 AT&T, Sony Xperia ion AT&T, Samsung Infuse AT&T(First Android Phone), All iPhones before that.