Verizon is very protective over their network and always has been. They used CDMA for years just to lock out outside competition amongst other walled garden bullshit. When they moved to GSM they still tried to lock their network to a whitelist of phone IMEIs they control. They do not want you to buy an unlocked phone from a brand they do not get paid by to be put on the whitelist support.

Concur. But gotta look at the frequencies, there is a chance most Verizon /visible freqs are supported

Verizon doesn't support a lot of unlocked devices even sold from major manufacturers