Some manufacturers are already distributing it, others have just announced it, and some have offered no update on the Android 9 Pie. Based on the current information available, we have summarized what it can do and who is missing what.
https://www.notebookcheck.net/The-Android-Pie-list-Will-my-phone-get-the-Android-9-update.396576.0.html
Bq announced Oreo for my X5 Plus a year and a half ago. Currently still on Nougat. I wouldn't trust that their update schedules will be "optimal".