So you would like to build your own crawler robot? The Yahboom Tracked Robotic Crawler Chassis has you covered. It has an aluminum alloy frame and can handle off-road conditions. It has holes for attaching Raspberry Pi and Jetson Nano boards.
This crawler chassis has 520 DC gear motors. It comes with nylon tracks. You can install cameras, LiDAR, and other sensors. This chassis supports a 3DOF robot arm.