Lineage OS can often do WiFi only on old Androids.

But unless I'm mistaken, if a device only has 3G, and you want to travel with it away from WiFi, you can't even get 3G data on the device, as they shut off the 3G networks in the USA. Best you're gonna find in some rural areas may be 2G or 2.5G.

That's fine. I still have my main modern device with my sim card and 5g and I can tether the old device to it for the kids to use in the back seat.

I'm not sure. In some rural areas in Oregon I seem to still get 3G (on Verizon). Unless my Android device is mislabeling 2.5G.

December 31st, 2022 is the last day for the Verizon 3G network.