He’s used silicone tracks and 6 V, 75-gear ratio micro metal gear motors, both by Pololu, an ESP32-S3 Feather board by Adafruit as the main controller, and designed a custom board to handle low-level operations such as maintaining consistent motor speed.
The sensors are where things get really interesting: among other things, there’s a 6 DOF Inertial Motion Unit (IMU), which can be used for determining robot orientation; two front-facing laser time-of-flight sensors, for detecting obstacles; and no fewer than seven sensors facing the ground, to enable line-following tasks.