Philpo explained it well.

I’m currently using Home Assistant as my integration platform to talk to everything, and as an automation engine to make things happen.

Home Assistant can then expose your devices to other platforms like Apple HomeKit and Google Home.

For controlling things manually, I mostly use the Apple Home app, and Siri and Google Assistant for voice control.

This year the Home Assistant developers are focusing heavily on building out native and local voice control. There will be an announcement in a week on their progress. It looks like they will be announcing the ability to use wake works to activate voice commands (like Google/Siri/Alexa but all done without compromising your privacy).