Google is testing out a feature on the Android app that might let you bypass saying "Hey Google" to activate Assistant. Android Police spotted a new "Guacamole" menu in the Assistant settings, enabling you to skip the usual hotword for "help with quick tasks" like answering calls and stopping alarms. AP pointed out that the Google Nest Hub has a similar feature for alarms since 2019.
When it goes live, you'll supposedly get to opt-in by reading terms and conditions before activating it. We say supposedly because the feature isn't live yet. We expect to hear more about it at Google's I/O conference next month.