So for the English model they use mostly free/open-source data, but some non-free data:
- train_files Fisher, LibriSpeech, Switchboard, Common Voice English, and approximately 1700 hours of transcribed WAMU (NPR) radio shows explicitly licensed to use as training corpora. (from https://github.com/coqui-ai/STT/releases/tag/v0.9.3)
As for the hardware for training... it's basically NVIDIA (you need Tensorflow / CUDA and all that guff). For inference it works realtime on a CPU.
I'm preparing pretrained models based on Common Voice data for their STT based on Common Voice data here: https://tepozcatl.omnilingo.cc/manifest.html
There is plenty of free/open-source voice data out there, just it's a question of reaching for a sick bag and installing NVIDIAs stuff.
I don't know if they'd count as free/open-source according to Debian (I'm a Debian user myself), but the team has definitely talked about getting into Debian and would be very open to discussions about it.