Why does the description focus on GSM?
All the major US carriers are using LTE now. ALL of them. AT&T, T-Mobile, Verizon, US Cellular and all their sub-brands and MVNOs. Everybody is LTE.
The GSM and CDMA networks have been deprecated or turned off.
If all this device can do is legacy GSM, which is all the description mentions, it must be really old and won’t be able to work on any carrier.
2020 release date.