https://www.theverge.com/2019/2/20/18233886/samsung-galaxy-fold-att-tmobile-verzion-sprint-availability

Samsung’s very fancy foldable phone, the Galaxy Fold, will be available on two carriers when it launches in the US in a couple months: AT&T and T-Mobile. As for everyone else? Samsung hasn’t said, but for now, it sounds like the initial model of the Fold won’t launch on Verizon and Sprint.

It’s not clear if that means the Fold outright won’t work on those two carriers, but that may be the case. Verizon and Sprint rely on a different mobile technology for their 3G networks, and it’s possible the Fold just doesn’t include support. Sometimes, unsupported phones can still access LTE on Verizon and Sprint, but it isn’t guaranteed.