Which is the better prospect of embedded software development or traditional software development, and why (which is convenient for starting a business)

The biggest difference between embedded software development and traditional software development (assuming you mean computers) is the problem of resources.

The development of embedded software is limited by the resources of embedded hardware, so we must use resources carefully, and then it is best to know something about the hardware.

Traditional software development does not have these restrictions.

At present, there is a huge amount of embedded software development, but when using different operating systems, your software will have to be rewritten because of the different man-machine interface. Of course, considering the quantity and future development, developing embedded software is more promising.