Web dev diving into IoT (Teltonika + MQTT) — looking for guidance

Hi everyone! I'm a web developer (React + Flask/Laravel) and I'm working for the first time on an IoT-based system. The setup: Buses have Teltonika FMM920 GPS trackers, which send data to a server with a fixed IP. That server decodes the data (probably using Codec8) and then sends it to me via MQTT. My job is to: Subscribe to MQTT topics Calculate ETA based on GPS + route info Display results in a dashboard (React) and on LED screens at bus stops I'm totally new to IoT protocols like MQTT + GPS trackers. Can anyone share a roadmap, tips, or how you structured a similar setup? Thanks a lot