Hints to software to build your own Google Home
Some guys are trying, however they are held back by production and fitting problems of PCB and LCD. Would've been easier if they had just used standard hardware I guess. But it's harder to charge for that.
https://www.kickstarter.com/projects/aiforeveryone/mycroft-mark-ii-the-open-voice-assistant
They do on the page mention a number of text to speech and command softwares, those could be worth to take a look at.
- Pocket-sphinx
- precise
- Mozilla DeepSpeech
- Adapt
- Padatious
- Mimic
- CMU flite
So there's probably where you hould start looking!