FMCA has what they call TECH CONNECT. This is a Sprint (now merged with T-Mobile) Wi-Fi hotspot.
Not one cellular company has 100% coverage but T-Mobile and Sprint are now sharing towers and I can tell you the gaps are shrinking (Driving from where I am now living a few miles due south of a favorite campground, to my Cardiologist (one of the reasons I no longer RV) a few miles due north of another formerly favorite campground (New management not good) I used to get gaps in T-Mobile.. NONE since the merger.
I've seen speeds ranging from "Ouch" to WOW And then some
Driving to Elkhart pre-merger My poor T-mobile phone hit zero NO SERVICE the Sprint device (The phone can link to wi-fi and still work) Hit.....
Well when I tied the phone to the Wi-Fi and hit the speed test the "needle bent around the pin" as it were. Right off the scale.
Normally back then I got like 20-30 Mbps Just enough for a video stream.