Pi 3B has the most flexibility. Pi Zero and Zero W can be easily connected to another computer as a USB dongle. They both have the memory to run most software.
If you have spare computer bits, you can connect up old disks to build a NAS. Learn RAID and all that stuff.
You could look for software design tools, like Pencil, to see if they run on a Pi. Most coding examples are in Python with some examples in C. There are downloadable books on both. Ask your course director what languages and tools are used in your course. Find what will run on the Pi.
If C or C++ is one of the languages you will use in your course, there are projects using C to write at the device level and some of those projects are cheap. Pick an I2C sensor. A few dollars, some wire, resistors. you can measure and track some input.
Some of the camera projects are interesting. Recognising number plates, faces, etc. A useful skill.
With a camera, speaker, and some really simple AI, your Pi Zero could replace a few politicians.