How does IFTTT integrate with Google Assistant to read voice commands without an explicit invocation phrase?

In IFTTT you can create an applet that connects to your Google account and gets invoked when you say certain phrases directly to the Assistant. I’ve worked on dialogflow chat bots with some complex interactions and fulfilment services but it was always for in house projects so I never really go to a point where my bots where being used in a B2C manner. So for these bots you’d have to say something like “Talk to xyz” to invoke your agent and then you could continue talking and interacting with the agent.

I’d like to recreate what IFTTT does with Google assistant now, so that I can have users sign up once and then use my chat bot directly from their Assistant device, without the need to explicitly trigger the agent. Can someone please tell me how this works or point me towards where I need to research on this?

Thanks for reading!