Note,it is important to discern the precise form. Exodus 17:9, “יהושע” is the first occurrence, but Numbers 13:8,16, demonstrates the compound design of this name. Names in the Bible are important and it seems the original Hebrew is unique in the Pentateuch. My original question was upon that note, only in Psalms 81:5 is “Joseph” written as a full compound “יהוסף”, all others are, “יוסף”. That is precisely the opposite case in which the variant form, “ישוע“ occurs only in Nehemiah 8:17, referring to Moses successor. The JPS note for “Jochebed” (יוכבד), has it as the first such compound name, yet the only other occurrence is Num.26:59 and in neither case is an etymology indicated. Could it not be like “Jephunneh” (יפנה) in Num.13:6, “he will be prepared” ? In that case her name translates as, “he gloried”, referring to her father or perhaps husband.
As “el” and “YaH” compound names seem to occur about equally in the other Hebrew texts, why do “Methusael, Ishmael and Israel” stand alone in Genesis? It seems to me that as The Hallowed Name is not to be given among men under heaven, this compound with “salvation” was chosen long before Joseph and Mary were told. Does that also have implications in understanding Ex.6:3?