They can't fix the issue. They're not certified devices and will never be (unless Google changes their CTS and certification rules)
I cannot speak for Onyx, but in Likebooks (in android 6, probably in newer versions too) toggling "Play Store Support" will change the fingerprint. The new fingerprint is spoofed from a device which is certified.
That's all. There're not more options. Or the device cames with a spoofed fingerprint from Stock or the fingerprint is changed on demand.
For lurkers, you can figure out which device is your ereader spoofing by typing
Code:
adb shell getprop ro.build.fingerprint
and doing a google search with the result.
This has nothing to do with nation politics,unlike Huawei, but with Google policies.