say "This is a test message" --voice="Bubbles"
say "This is a test message" --voice="Organ"
say "This is a test message" --voice="Good News"
say "This is a test message" --voice="Bad News"
say "This is a test message" --voice="Jester" $ apt install espeak-ng
$ espeak-ng 'Hello, World!'
If there's a more modern package that sounds more human that's a similar no-brainer to install, I'd be interested, but just to note that this part of the problem has been solved for many years now, even if the better-sounding models are usually not as openly licensed, orders of magnitude more resource-intensive, limited to a few languages, and often less reliable/predictable in their pronunciation of new or compound words (usually not all of these issues at once)
$ apt install festival
$ echo "Hello, World!" | festival --tts
$ sudo apt update
$ sudo apt install -y python3 python3-pip libsndfile1 ffmpeg
$ python -m venv piper-tts
$ ./venv/piper-tts/bin/pip install piper-tts
$ ./venv/piper-tts/bin/python3 -m piper.download_voices en_US-lessac-medium
$ ./venv/piper-tts/bin/piper -m en_US-lessac-medium -- 'This will play on your speakers.'
More crazy: Home Assistant did a "Year of Voice" project (https://www.home-assistant.io/blog/2022/12/20/year-of-voice/) that culminated in a real open-source voice assistant product (https://www.home-assistant.io/voice-pe/) !!! And it's only $60??
It has some mispronounciations in the texts I tried to listen to, besides using so much RAM that it kills basically all other apps to make space for this. Not really worth it when espeak is already understandable
Festival I've tried in the meantime and doesn't support Dutch or German, two of the three languages I use regularly. I keep coming back to espeak at the only option that will simply always work xD