I have a subscription to Gaia pro and an older Nvidia Shield tablet; I may try that. I picked up Maps Pro and bought the North America maps to see if that works. I'm going to try pairing the GPS in the ICOM with the Surface this week to see if that works. If all else fails, I'll buy an iPad with a SIM and use that like you are suggesting.I run an iPad with cellular with Gaia pro and have never been disappointed. FWIW.
I bought the NA Maps in Maps Pro - going to pair it with my Icom as a GPS (hopefully).If you go this route let me know how it works. I have a Surface Pro, and love it but have not found a good mapping app for. The windows part and the lack of GPS seems to be the issue. I am trying to get it to recognize my Garmin through Bluetooth but no luck yet