[bserge]

https://snowboy.kitt.ai/ is about the only good third party hotword detection engine. You can hook it into Assistant with a bit of work, and with Tasker/Automate and a rooted phone, you can open apps, press buttons, pass voice commands, and more.

Imo, Assistant is limited because of privacy, see how it asks you to opt in for a more personalized experience and it still won't unlock your phone for you.