You can make this app yourself in an hour if you're on Linux and can do some scripting. Mockup below for illustration, but this is the beating heart of a real script:

  # whisper-live.sh: run once and it listens (blocking), run again and it stops listening.
  if ! test -f whisper.quit ; then
    touch whisper.quit
    notify-send -a whisper "listening"
    m="/usr/share/whisper.cpp-model-tiny.en-q5_1/ggml-tiny.en-q5_1.bin"
    txt="$(ffmpeg -hide_banner -loglevel -8 -f pulse -i default -f wav pipe:1 < whisper.quit \
      | whisper-cli -np -m "$m" -f - -otxt -sns 2>/dev/null \
      | tr \\n " " | sed -e 's/^\s*//' -e 's/\s\s*$//')"
    rm -f whisper.quit
    notify-send -a whisper "done listening"
    printf %s "$txt" | wtype -
  else
    printf %s q > whisper.quit
  fi

You can trivially modify it to use wl-copy to copy to clipboard instead, if you prefer that over immediately sending the text to the current window. I set up sway to run a script like this on $mod+Shift+w so it can be done one-handed -- not push to listen, but the script itself toggles listen state on each invocation, so push once to start, again to stop.