Patrick is absolutely correct that this is a function of the synthesizer(s) in use rather than NVDA itself.  When faced with an unpronounceable sequence like FL10 (F L 1 0) it's got to "take a guess" and since FL is a state abbreviation it makes at least some sense to try "Florida ten."  In the case of NV-Access or NV Access it makes perfect sense to "guess" that NV would be Nevada.

The NV-Access or NV Access case is easy enough as far as a regex match with substitution.  FL10 would not probably require a regex, but that really depends on exactly what it is you're trying to change and how many variants on the pronunciation you need.
--

Brian - Windows 10, 64-Bit, Version 21H1, Build 19043  

I do not understand why some seek to separate a person from their actions.  The self is composed of an individual’s thoughts, actions, and expression, which are contained in and actuated by the body.  What you do and say is the clearest indicator of who you are.

      ~ Brian Vogel