Let me say this: I do not think that the Sea Peoples were a homogenous ethnic group. It's very obvious they weren't. Also, even though some of the Sea People names recorded in the Egyptian sources sound similar to the names of later ethnic groups (such as "Shekelesh" as Sicules, or "Sherden" and "Sardinians", this is unfortunately little more than speculation).
One example I would like to comment on are the "Thur(i)sha" and their equation with the Etruscans. One problem is that the Etruscan endonym was "Rasna" or "Rasena". In contrast "Tyrsenoi" (which is supposed to be a cognate of Egyptian "ThRSh") is a Greek exonym. On the other hand, there is the possibility that Tyrsenoi is derived from Ras(e)na.
Regardless of this, it is reasonable safe to assume that the Sea Peoples invasion, and the Bronze Age collapse in the Eastern Mediterranean was not limited to that region, and that there is evidence for widespread turmoil and upheavel in much of northern and western Europe. So, even if the Sea Peoples were not directly related with the movements of peoples in northern and western Europe, they were part of the same phenomenon.