If you're of the "I don't care what I sound like, I don't want any surgery and I just want to train my voice" mentality, then you basically want to look into what's called counter-tenor training. There's a very well-established tradition in this area and it is possible to sound rather good.
The catch? Don't try singing Britney Spears with it. It's a very formal, classical sound best suited for choirs or Nessun Dorma. It also will not sound anything like your normal speaking texture or register, and this is something practice really will not help with.
If you actually want to improve your singing voice with VFS, well, good news! It does make the counter-tenor technique considerably easier: you will likely have less difficulty navigating your passagio, and have a more naturally female sound when singing in any register. My experience now is that I don't really feel like I'm making undue effort to sing
If you don't study/practice, and don't have surgery, well don't expect any miracles. If you have a voice that just never passes, probably VFS is your best option, since even with counter-tenor technique you'll still have a very "covered" or muffled sound, like a heavyset woman with a cold.
(Source: Focused on this for over a decade, had VFS. I pretty much know what I'm talking about.)