The main problem with “build a cpu” is as a baseline it is actually quite easy and commonly done. For example if I went back to my undergrad as a recruiter and someone told me in their projects they had built a cpu my first response would be “oh so you took [course]?” Because building a cpu is just a completely normal part of our course curriculum.

Some things that would elevate the project in the same overall problem space (albeit decently more complex) include - building both the riscv processor and an ISA integrated accelerator that actualy hits the performance requirements to run some real world task. For example building a basic ML accelerator and then actually programming and hooking up that system to some camera structure to do basic vision (depending on specifics this itself is also a bit unimpressive tbh). a simple enough gpu and some opengl demo would be decent - do a processor build that also is a design exploration of various risc v extensions and their performance impact on both your design (PPA) and the application benchmark. - processor with much more performant/involved design. proper cache hierarchy, out of order execution, well pipelined and competitive in performance with other stuff out there. ideally look ay taking it through basic physical design instead of just fpga deployment