I have an off grid space that I work from. For connectivity, I use a 5G phone on T-mobile with the EasyTether app (which tethers over USB and doesn't count as hotspot data). I have an RPi connected to the phone and a travel wifi router connected to the RPi over ethernet.
That said, 5G service is pretty good in my location, speeds are fine, but isn't the cheapest solution ($70/mo.
I second easytether! I use this from my at&t Samsung s9 and it works incredibly well in USA. I have it usb to a pi which runs dnsmasq to operate as a router with both an Ethernet switch and WiFi access point. Toss on a UPS and plug it into my truck. When I’m driving it charges and they make 12000mAh batteries so it lasts a full workday. I’ve used over 100Gb from this setup per month for over a year. I also tried out a cellular hat for the pi and found that it was a pain to setup but in the end can replace the cell phone.
That said, 5G service is pretty good in my location, speeds are fine, but isn't the cheapest solution ($70/mo.