I have a Google Nexus 5X with a Ting GSM SIM. I'm still running Android Nougat (7.1.2) and when I check for updates the phone cheerfully tells me it is up to date. (My wife has the same phone on Verizon and was updated weeks ago.) The update has been out about a month and I believe I should have gotten it. Is the delay the result of the carrier (TMO?) I thought the Nexus phones purchased from Google got updates directly from Google? Any insight into getting Oreo on my phone is most welcome! (I still have a Ting CDMA sim and could switch to that if it would make a difference.)
I've also tried sideloading this following directions at https://developers.google.com/android/ota but when I put the phone into recovery mode it does not appear in the ADB device list.