The driving experience with Android devices has been a bit hit-and-miss down the years, it's fair to say, with features and modes appearing and then disappearing, and Android Auto going through a few changes as well since its 2014 launch. Android Auto was originally available on both phone screens and vehicle dashboards, before being replaced by Google Assistant Driving Mode on handsets. As Gemini emerged, Driving Mode disappeared as well, which means there's now no customized interface for driving on Android devices themselves—everything gets handed off to Android Auto.
However, with the help of Headunit Reloaded Emulator (an app I found thanks to How-To Geek), you can override Google's decision and get Android Auto back on your phone. You can also beam the Android Auto interface to another Android phone or tablet. It's a $4.99 purchase, but it works as advertised—or at least it did with the Pixel and Galaxy phones I was using. If you don't have an Android Auto-compatible dashboard in your car, you can use this to get the same experience on your main handset or on a spare phone or tablet you've got.
I should note that there are some bad reviews of this app on the Play Store, though it worked perfectly fine for me. Users complain about about flaky performance and difficulties with certain phones—so it's worth reading through to see if your handset is mentioned—although others give the app a full five-star rating and seem happy with how it worked.
As always, remember the dangers of using your phone while driving. This is specifically for emulating Android Auto on a screen other than your built-in head unit—the other functions on your phone should stay unused until you're safely parked up.
Setting up Headunit Reloaded Emulator
Once you've installed Headunit Reloaded Emulator from the Play Store, you need to approve all the permissions that allow it to work, including Bluetooth and location access. When you're in the app, you'll see your three mode choices: Phone Mode (for using it on the current handset), and Wi-Fi and USB (for connecting to another device).
Tap Phone Mode to get Android Auto on your handset's own screen. It might not look great at first due to the cramped display size, but if you turn your phone around to its landscape orientation it should fit nicely. Any taps on the screen register just as they would on Android Auto, and you can switch apps and change the layout via the icons down the side.
To quit the interface, you need to go back inside the app rather than exiting it completely: On most Android handsets, this is now a left-to-right swipe on the left edge of the screen. A row of options shows up, including options for exiting the mode and even running it in a picture-in-picture format on your screen.
Back on the main screen, you're able to access a wealth of options under Settings. These cover everything from pixel density and screen margins to key press configurations and audio routing—you can pipe the audio from apps through your car's speakers via Bluetooth if you want, even if the Android Auto interface is on your phone.
Connecting to another device
If you have a separate phone or tablet you want to get Android Auto running on, then you need to get Headunit Reloaded Emulator up on this specific device—the one acting as the head unit (control center) in your car. You can then connect your primary phone to it, using that phone's apps and data.
The USB option is easier, if you've got a cable to spare and are happy to keep both devices hooked up during the course of your drive. Connect the cables, then on the device running Headunit Reloaded Emulator, tap the USB option on the main screen and select your main phone when it appears. On your main phone, you may need to tap the USB notification and choose Transferring files / Android Auto as the connection mode before it works.
There's a wifi option as well: You need Headunit Reloaded Emulator running on the device that's displaying Android Auto, and the companion Wi-Fi Launcher app on your primary phone (driving the maps, apps, and info on the Android Auto screen). On the former device, choose Wi-Fi as the connection method inside Headunit Reloaded Emulator, and make sure the latter device is set up to be discovered in Wi-Fi Launcher.
By default, both devices need to be on the same wifi (your car's built-in wifi for example). You can also use a direct wifi connection: select it under Wireless in Wi-Fi Launcher, and under Settings > Connectivity in Headunit Reloaded Emulator. One device will then drive Android Auto on the other—no connecting wires needed.