While CircuitPython does not have native or library text to speech (as of yet), there are services for Python 3 if you are running on a single board computer (SBC) like Raspberry Pi.
Google Text to Speech
gTTS, Google Text-To-Speech is a Python library from Pierre-Nick Durette that converts a string into an audio file. It does not automatically speak, rather it creates an mp3 file that we can then play.
See this post by Les on how to set up gTTS.
Polly is Amazon's text to speech engine. You will need to sign up for a AWS account to use.
If you build voice-enabled projects, post video or links to them on Twitter tagging @Adafruit, we'd love to see what you are making.