I actually just did something similar with whisper.cpp, and hooked it up to GPT-3 Davinci-3 via the API, and then the answer piped via Microsoft's text to speech. The mic I'm using is a cheap USB omni-mic designed for conference calls.
In terms of what other assistance can't do, it can integrate w/ my desktop computer in a way that other assistance can't easily do. The M$ voices take things to another level. Apple has better quality voices for Siri on desktop, but they don't let you access them through the 'say' command.
[0] https://writings.stephenwolfram.com/2019/02/seeking-the-prod...