There is no better way to learn programming and robotics than building and programming your own. This Autonomous (LIDAR) Litter Detection Robot is an interesting project that gives you an idea what it takes to build a robot that can recognize and monitor litter.
This robot is driven by a Raspberry Pi. It comes with object detection, anti-fall system and video streaming. You are going to need a Raspberry Pi 4 Model B, DFRobot RPLIDAR A1M8-R6, Arduino Nano R3, USB web cam, and a few other parts to pull it off.