Sharing LTE connection over Ethernet?

Would the Sixfab Raspberry Pi 4G/LTE Cellular Modem Kit make for a potentially good LTE failover or mobile hotspot over Ethernet solution? (Failover WAN on a UniFi Dream Machine)

The Sixfab PAYG rates are pretty reasonable for low data usage, and I think the PAYG model makes more sense for a failover application versus paying for data per month as the outages will only happen for a couple hours at a time every couple of months. The next cheapest alternative I can think of would be something like a tello monthly plan with an LTE modem.

Would you guys recommend sticking with Ubuntu Server 20.04 or trying something like OpenWRT for that kind of application?