Something I've been seeing about the source code in Android Q is, carriers can list allowed and blocked carriers. A phone could accept a SIM card from the primary carrier while blocking MVNOs that run on the same towers. This would be allowed on both single and dual SIM card phones.
Would this be only on carrier branded models? IOW, would a Verizon Pixel have these restrictions, while an unlocked Pixel from Google would not?
@scottb that's the Android Police and other site's take. I'm guessing it's based on this comment in one of the commits (https://android-review.googlesource.../android/telephony/TelephonyManager.java#8906): Code: This method works only on devices with android.content.pm.PackageManager#FEATURE_TELEPHONY_CARRIERLOCK enabled. Presumably that flag will be disabled on Google sold models.