What are the alternatives? I'm seriously not aware of any that fulfill all of the abilities that an Alexa or Google Home has. I can imagine an offline version that does most of what they do but as far as I know they don't exist.
I'm not the person that you responses to, but Home Assistant offers most of the automation capabilities that the Alexa platform does. I haven't yet looked into the speech-to-text interface alternatives described here: https://news.ycombinator.com/item?id=29561452