It is 2019 and I’m not sure we have such useful app which might help a lot in online activities. I tried looking for such app but never saw any.
One interesting thing is that i saw an article back in 2004 claiming some scientists were developing such an app. Also online i saw some thesis explaining how the Swahili TTS would work.
Now its over 10 years, others have advanced in the technology but huku tunadepend vitu za wazungu tu.