So I'm not personally locked into CDMA vs gsm, its just that the carrier appears to be. The exact quote from the device page is
"[US Version] Compatible with GSM Networks including AT&T, T-Mobile and MVNOs (Mobile Virtual Network Operators) who utilize AT&T and T Mobile networks. This device is not compatible with CDMA Networks such as: Verizon, Sprint and US Cellular"
Looking at it more, it sounds like the problem is specifically the 13 band not being supported by the device.
Checking the bands is the difference from having slow, basically 3g speeds, and having full lte and 5g.
Most modern phones support the common 4g bands, a few years ago stuff like 700 and 1900 weren't as uniform, but 5g is critical, everyone has their own bands and there's a really good chance you might only get a minimum and highly oversubscribed band between your carrier and phone.
CDMA and GSM are both dead in the US. However MVNOs, who contracturally not allowed to mention the name of the MNO they operate on, have adopted the convetion of using CDMA to refer to Verizon and GSMT or GSMA to refer to T-Mobile or AT&T.