Phone Upgrade

I've been an Xfinity Mobile customer since December 2019 with 2 lines and a shared gigabyte of data.  In the time since, we've never gone over the 1 gig, as we don't stream/game and the phones mostly stay on WiFi.  I upgraded one of the phones for the first time last summer with 24 monthly discount credits.  I would like to finally upgrade the other phone, but I'm being told that I would need to upgrade my plan to an Unlimited plan in order to qualify for any device discounts.  That would immediately raise my monthly bill by over $40 for data that we do not need.  And then I'd still be paying monthly for the device.  Also, I'm concerned that switching from my current plan would also risk losing the discount I currently get on my Internet/TV bundle, increasing that bill as well.

So I'm just wondering if there are any other options for long-standing customers that just want to upgrade to a modern phone?  I'm not looking for a high-end device -- but even a full-price moderate phone is still $400-$500.  Though paying $400 for a device is still actually less than the over $500 ($480 + device + tax) my bill would go up if I switched to an Unlimited plan for a year.  (And that's assuming I don't lose the current discount on the Internet/TV service.)