So far, only a few OEMs like OnePlus, HMD Global, and Sony have sent out the stable Pie update. Thankfully, the Android One program exists to combat that, and it's been rather effective so far, with a number of Android One phones receiving the update to Android Pie last week.
https://www.notebookcheck.net/Multiple-Android-One-phones-receive-Android-Pie.363096.0.html