According to XDA, the Heads Up feature is rolling out only on the Google Pixel series of devices. Not entirely surprising, since the Pixel phones usually get new Android features earlier than any other. No word on when it will be available on devices by other brands just yet.
The Heads Up feature is another entry into overarching Digital Wellbeing umbrella, first introduced in Android 9 Pie. But it’s quite unfortunate that we’ve come to the point that we need our phones to remind us to watch where we’re going.