This dirt cheap 4G LTE modem on a USB stick can be hacked to run mainline Linux - Liliputing
Amazon.com: 4G LTE USB Modem WiFi Dongle, Mini Portable USB 4G Wireless Network Smart Router for Tablet Laptop Notebook, 2 LED Status, Plug and play(US Standard) : Electronics
Amazon.com: WiFi Modem Dongle, 4G LTE WiFi Modem, WiFi Modem Dongle with SIM Card Slot, TDD FDD GSM Car WiFi Mini Wireless Router with LED Status Indicator, Up to 10 Associated Users
MIKROTIK 2.4GHz access point with 4G (LTE) International modem, LtAP LTE kit (RBLtAP-2HnD&R11e-LTE) - The source for WiFi products at best prices in Europe - wifi-stock.com
4G LTE Modem Wireless Router USB Dongle Mobile Broadband WIFI SIM Card USA lot | eBay
4G LTE Modem Wireless Router USB Dongle Mobile Broadband WIFI SIM Card USA lot | eBay