Google Assistant may be gaining a new trick soon.
Google is currently testing the ability to send text messages using Google Assistant with your screen locked. Currently you can compose texts with Google Assistant, but your phone will prompt you to unlock your phone to continue and actually send the message.
The ability to use Google Assistant to send texts with your screen locked is currently in A/B testing. That means that it's only available to some users and there's no easy way to enable it for yourself, as the folks at 9to5Google got it on a Pixel 3 XL running Android Pie but not on a Pixel 3 running Android Q.
Being able to use Google Assistant to send a text message without unlocking your phone could be super handy since you could chat without having to enter your PIN or use another unlock method. Some could see this as a security issue, so if Google does roll out this feature widely, hopefully the company will have an option to let you require your phone to be unlocked before Google Assistant will send a text.