I am using abbreviations for well-known phrases: e.g., "Nash equilibrium" becomes NE and "neural networks" becomes NN. Should I use "an NN" or "a NN"? Does it matter whether a reader "unfolds" the abbreviation or not when reading? That is, I think it is often the case that NE is read "Nash equilibrium", then it seems appropriate to use "a NE".
The pronunciation depends on the words you Utter but not on the phrases , if your abbreviations are acceptable and understandable.
If you pronounce NE seperately , then it is an N E or or if it is pronounced like a single word NE , It becomes a NE, if it is well established like WHO.
NN can be pronounced only seperately so an NN is the only option.