US cellular service (as I understand it as of post date)

[rocket2nfinity]

With any phone that supports VoLTE and is not on a carriers whitelist, the trick to activate has been to use an MVNO that does not care what your device is. You do need to provide an imei for a device that is approved on their parent network (which is what they provide the parent network). Then simply put the sim in your Pinephone, or other android phone, and you're good.

Red Pocket and US Mobile are good choices, some don't even require the imei from an authorized device.