Upgrading iPhone through Apple's Program with a non-listed carrier

I have used the Program for a number of years to upgrade my iPhone yearly. After my last upgrade to iPhone 16 Pro I switched my carrier from Verizon to Consumer Cellular and want to stay with them now. However there appears to be no way to upgrade now without selecting one of the Big 4, having Apple activate the new iPhone with with my current phone number with that carrier and then switching back to Consumer Cellular after I receive the phone. This seems unnecessarily complicated, time-consuming and user-unfriendly. Lots of ways the process could get messed up along the way. Isn't there a way to just upgrade to an unlocked iPhone and then select the carrier after I receive it? Apple chat and telephone support don't seem to think so, nor do the folks in the Apple Store. You can do it if you buy an iPhone outright but I'm still paying off my current one. Because this seems like such an unnecessary hassle, I'm seriously considering skipping this year's upgrade, waiting another year until my current phone is paid off, then ditching the Program and just buying the next model with my current phone as a trade-in. Any wisdom/experience with this?

[Re-Titled by Moderator]

Original Title: Isn't there a way to use the iPhone Upgrade Program with a carrier other than the 4 that Apple lists during the upgrade request process?