Google promised that an assistant driving mode for phones would arrive in mid-2019, but it clearly did not happen – over a year went by without a sign of it. However, it seems to be ready. XDA developers have discovered (via Android Police) that Google Assistant’s driving mode is at least partially enabled for Android users. The interface has changed significantly from the I / O 2019 demo, as you see above, but the concept remains the same with large buttons and text that allow you to chat, send messages and play music while keeping your driving distractions on a minimum.
The rollout appears to be on the server side and may be part of a test. It is not linked to any specific versions of Google Maps or search apps and also works on a number of devices. Your access may depend on your account.