Paver Base ... pea gravel depth?
If you are down 2' and are still in pea gravel and muck, I would just use some good road base conpacted well to bridge the bad soil and the that will support a sidewalk. Single size aggregate does not compact if the particles are rounded and crushe, angular rock without some fines is not much better.
Since it is just a sidewalk, the loads are minimal. I would not pour concrete or anything important over it because of possible differential settlement or frost heaving/movement and tripping problems.
An interlocking concrete paving stone sidewalk would be fine for a sidewalk or even some heavier loads because it is a "flexible" surface that maintains strength since there are no new movement cracks and it depends on the compacted base for reliable support and not just a couple of inches of concrete. I have seen pavers used for 60,000# loads on 20 acres sites about 4' above sea level. What you want is a even, safe, hard surface without any surprising cracks or trip points.