Another manufacturer that promised its Android 5 device could be upgraded to 7 then disappointed its customers when it found out the hard way the phone didn't work on 7:
[ltr]X1 Update Apology[/ltr]
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[color=#90949c][size=85]AGM SMARTPHONE·THURSDAY, MAY 10, 2018https://www.facebook.com/notes/agm-smartphone/x1-update-apology/435477696876837/#[/font][/size][/color]
[ltr]Dear X1 users, we're sorry for the troublesome experience and the confusion related to the software update of the AGM X1. This is not the experience we want you to have. Before the X1 was launched, we had finalised the software on the device. After several requests from customers, we began developing software for X1 since January 2017. While working on the development of the 7.1 software, our engineers found an obstacle which was far beyond the original roadmap. The new software could not work very well on the X1. The only way to run this new software was to change the X1 PCBA, which meant making a new X1. The current X1 hardware does not support this update.[/ltr]
I would much rather Blackview got it right on every phone they released, than wasting precious time on trying to make older phones work on Android 8....if it was working perfectly they would have released it by now. Don't push them to be hasty...you might regret it.