Yes NuGet is one issue with SharpDevelop, there are ways round it. The absense of .Net Core (it only has .Net Framework) is a bigger issue going forward. However SharpDevelop is great if the bloat of VS is too much for your hardware.
The intellisense works inyour extension, but the NAudio dlls do still need to be copied manually - there are ways to handle this but they involve merging them into your dll, or holding them as resources and copying them into exe folder at runtime. I wouldn't worry about this at this stage, just maybe leave a ReadMe instructions in your download - to be honest it will probably only be a couple people look at it in development.
The intellisense works inyour extension, but the NAudio dlls do still need to be copied manually - there are ways to handle this but they involve merging them into your dll, or holding them as resources and copying them into exe folder at runtime. I wouldn't worry about this at this stage, just maybe leave a ReadMe instructions in your download - to be honest it will probably only be a couple people look at it in development.