I looked into this a bit yesterday and had similar issues. One hacky option on Mac could be to [1] use BlackHole virtual audio device as the system default input (which Claude expects), [2] vibe code some app that can pick your actual mic as the input device (browser engines seem to have a pretty good support for this stuff), [3] stab a speech-to-text model there (whisper or lighter) that detects the wake word from a stream and [4] proxies the audio after that to the output side of BlackHole. I did not try it myself yet, though.