Looking back on my emails I see some correspondence from Michael Rainey AA1TJ about a sound powered CW TX he built. I think Michael's TX involved converting sound from his voice into CW RF. I have seen other circuits that convert the action of pressing the Morse key into RF. In theory, this would also work with speech. Of course, physics dictates that low milliwatts only can be achieved.
If you know of ideas, please let me know.