Question: Can I write my own assistant on mobile devices that is an actual assistant? As in, can listen for the key activation word in the background? Like the "official" assistants.

As far as I can tell, the assistant APIs seem to be like plugins? On Android for example, it appears custom assistants still run through Google assistant.

I want to be able to say "TriggerWord, do X and Y" and the OS activates my app, passes the voice sample and I take care of all the language processing from there. Which doesn't seem possible...