Not available in your area means that in Republic’s estimation, cellular coverage with its GSM network partner will be inadequate. Fortunately, should that prove to be true, a Moto G6 is also compatible with Republic’s CDMA network partner (Sprint).
Nevertheless, you’ll need to acquire a Republic bring your own SIM, which is GSM as all bring your own phones must first activate on GSM. You may do so here: Republic Wireless SIM Card Kit | Republic Wireless (ignoring any warnings Republic’s online store may present). That said, Republic’s fulfillment center is closed through tomorrow for the holidays and doesn’t expect to ship orders again until Friday, December 28th. You may want to get the SIM from Amazon for faster turnaround.
If Republic’s estimation that GSM coverage is inadequate turns out to be correct, here’s how to request a switch to CDMA: How to Request a 3.0 CDMA SIM Card – Republic Help.
Merry Christmas to you as well.