Pykrete does have one advantage over concrete boats - it isn’t porous. Reinforced concrete is very prone to leaks, and the steel reinforcement then gets damp with the expected results. Selling a concrete boat is very difficult because what marine surveyor would want to make a categoric statement on its likely long term seaworthiness? It’s one of those things that looked like a really good idea but turned out to be less than real-world practical - like Pykrete.
I think while you were composing that, I already posted. But the story is worth telling twice.
