So yes one outcome of such an assessment could very well be "lets end E2E encryption" but it could just as well end in simply stating that such a method is not possible.

no it was evidence collected by Sweden, Denmark and Germany by simply following the boat used. The boat was traced back to Germany and in Germany it was made clear that it was hired by a bunch of Ukrainians. Later it was also told by the Ukraines themselves that Zelensky had thought about it in a hypothetical way but then some one else high up in the military chain decided that it was a good idea.

The whole idea that the US somehow would be able to conduct such an operation is ludicrous, the path in, The Kattegat strait, is among the most surveilled pieces of water on the planet so the US would have had to conduct a clandestine attack by land through Poland/Germany and then on Swedish territorial waters all for nothing (Biden had already managed to get the pipe closed down long before the attack so there was zero interest from the US to do anything with it).