so it seems we have to wait for elivia… I just switched completely to /e/ OS including locked bootloader (oneplus 7t pro) and searching for a simple assistant since months… most of the stuff is incredible outdated or in alpha state. really interesting how many approaches exists but no one is really finished. The MyCroft approach is using Google voice recognition so is not an option too. at least not if that does not change:
Taken from their github page:
It implements voice recognition and Text To Speech (TTS) via Google API’s at the moment, but that may change soon.
I REALLY like the approach of having the whole thing on the device itself without any need of a network connection or own server but again… alpha 
https://github.com/Tadashi-Hikari/Sapphire-Assistant-Framework
So there is no development on Elivia since 9 months which leads me to the conclusion there will be nothing (usable) anytime soon… even not in months. I hope I am wrong but that is the frustrating result after my research.