Very confused rank newbie looking for advice

With care you can get the nios to execute very small C functions with no external support libraries (you need to set 2 registers then jump to any C function).

Rip out all the caches and run from 'tightly coupled memory' and the cpu footprint is about 2500 LEs - not a lot in the modern fpgas.

So the whole thing will be a lot more flexible than the 8051/pic stuff.

Not sure I'd want to run something as big as Linux (or even a normal embedded os) on the nios though.

But for a bare board, run some code for a small app it requires a lot less hardware setup than the SoC systems - partially because the hardware config removes a lot of the stuff that the software would otherwise have to do.