Actually, the problem is not whether you can pronounce it or not. The point is more likely whether you can use it correctly or not. As I wrote, there are rules which one(鼻濁音 or plain "g") should be used, thus, there are cases 鼻濁音 shouldn't be used even for "g" in the middle of words. For instance, が in 小学校(しょうがっこう) "elementary school" is 鼻濁音, but the one in 高等学校(こうとうがっこう) "high school" is plain "g". Actually, the rules are sometimes confusing even for native speakers. Also, note that the correct use of 鼻濁音 indeed makes your speech sound elegant, but incorrect use of it could be considered as rural regional dialect.