I’d assume the compressor would essentially work more like a limiter only, since there is immediate decay/0 natural sustain to actually compress.I use an EQ, a compressor and reverb on my banjo. You can tone shape, level out notes and get that high lonesome sound.
I’d also assume it would do an amazing job of making the response across the neck fairly even (my limited experience with banjo was that left to their own devices, can have a lot of loud spots and dead spots across the neck)