I used the sealskin socks once and gave them away as my feet had never been colder.It was an icy day , cold water got in and was trapped resulting in painful cold feet .
Yet sailing wetsuits work on a similar basis and keep you relatively warm in cold water – trapped water can be an issue in socks if it doesn’t warm up but overall insulation is still the thing that keeps you warm and a single pair of socks won’t do that unless you have really warm boots.
I go for ‘warm when wet’ kit generally – waterproof is a great concept but in reality all it does is slow down the rate of getting wet. You still need insulation.
edit to add, I have some seal skins socks, they’re great, especially over a thin wool sock and usually with winter boots or shoe covers. My old ones have worn a hole in the heel and they still keep me warmer overall in the wet than a normal sock.