The media outlet Android Police asserts that the OnePlus 8 will be compatible with Verizon's 5G network when it is released to the US market. Not only that, in fact, but it will also apparently launch through this carrier. However, the OEM already has such a partnership with T-Mobile in the same country.
https://www.notebookcheck.net/The-OnePlus-8-may-launch-as-a-Verizon-5G-device-in-the-US.450046.0.html