Typically when I hike, I wear my sock liners, compression socks, and if it's colder, my wool socks.
I am planning to purchase some waterproof socks because it's cheaper than buying another pair of shoes (and i've heard the waterproofing spray is not that amazing, but I don't want to wear FOUR pairs of socks on my upcoming trek, but I don't really know what sock I can get rid of. Are waterproof socks warm enough to get rid of my wool socks? Or are their compression socks that are waterproof? I have found all 3 of these to be of equal importance on a dry hike so I'm struggling to decide which I can switch out for the waterproof sock.
It's not clear whether you want warm or dry feet? Since water can come from the outside (rain, wet vegetation, creek crossings, slushy snow, etc.) and from the inside (sweat), I'm not sure absolute foot dryness is possible if you're active. So it's a trade-off where the usual goal is warmth rather than dryness. Years ago, I tried vapor barrier liners. While my feet were marginally warmer, they weren't dry (and the liners wore through pretty fast). Lately I've been using neoprene socks for winter hiking (in place of my usual summer wool socks) and cold-water rafting. In both instances they keep my feet warm but not perfectly dry. I haven't tried them, but you could consider Crosspoint Waterproof Wool Socks.
I'm not sure you've ever seen this before - https://www.soutdoors.com/best-heated-socks/ some pros and cons may help out. I've never used ones of them. Just recall there is some reviews about the heat socks. Hope it can help you.