Pixel 4 car-crash detection can now be sideloaded onto older Pixels thanks to Android 11 Preview

https://www.apkmirror.com/apk/google-inc/personal-safety/personal-safety-1-1-286909525-dogfood-release/personal-safety-1-1-286909525-dogfood-android-apk-download/

Note this only works for Pixel Devices