I worked for 5 years while traveling (every 1-3 weeks) across the country. I carried cellular plans with both Verizon and AT&T. And since I had a 9-5 that expected me online, cellular service was my #1 priority when evaluating camp spots.
I carried an antenna for my hotspots, a cell booster, and installed a router in the RV for a strong internal wifi network.
https://learntorv.com/cellular-wifi-and-networks-oh-my/
If you use hotspots with antenna ports (Verizon Jetpacks and AT&T hotspots), this cheap antenna worked in way more places than my expensive booster did.
https://learntorv.com/netgear-hotspot-antenna/
And it's expensive, but a membership to
RVMobileInternet.com can be good to get an idea of what offerings are out there at any given point. Lots of great info, but just kind of an expensive membership cost to get access to the full info.