What i forgot to mention is that the robot is 10x10x7cm big (WxLxH, 2.5x2.5x2.1in). It uses the blue pill board as the brain, i am not sure if this chip is enough for implementing ROS.
Regarding 4WD, i thought about this, but the size is small and turning like a tank with rubber tires needs a lot of power. The solution to this would be to use a tracka ssembly but this omplicates the mechanical part, as right now i can find the parts cheap on ali. The robot is not thought for this. Currently it has 2 motorized wheels and a ball caster as the 3rd support point.
The main purpose for the robot is a educational platform for beginners in electronics/robots/arm development. You can buy the robot(different assembly variants) and programmer as a package and install openSTM32. Afterwards clone a git rep and have sample code for every function.