Using 4G LTE wireless modems on a Raspberry Pi | Jeff Geerling
Cellular Modem & HAT for Raspberry Pi - 3G/4G/LTE/CAT-M1
IoT Bit 4G & LTE HAT for the Raspberry Pi - Hackster.io
Raspberry Pi Skywire Adapter | Airgain
Sixfab Raspberry Pi 4G/LTE Cellular Modem Kit | eBay
Amazon.com: 4G / 3G / GNSS HAT Module for Raspberry Pi Zero/Zero W/Zero WH/2B/3B/3B+/4B/Jetson Nano, Based on SIM7600A-H , 4G Communication and GNSS Positioning Module Support LTE CAT4 up to 150Mbps :
IOT BIT (Formally Known As PiAnywhere V1.31) 4G & LTE Hat for the Raspberry Pi : 10 Steps (with Pictures) - Instructables