Your question seems to assume that one could have, or needs to have, "proof" for pious devotions. This is by noi means the case.
It's as if to say, "prove" to me that refrigerator magnets portraying "Praying Hands" were taught in Scripture or were thought at any time prior to 1928 to be permitted in a Christian home. :o)
St. Joseph was (as we know from Scripture) protector of the Holy Family, hence of the Christ Child; we may (again, Scripturally) consider ourselves Christ's brothers and sisters, and hence part of His household (the Church); and from that, St. Joseph is seen as protecting us. And he's not the only one. We all -- all! --- share spiritual goods with each other through prayer. This is known as the Communion of Saints.
Pretty straightforward analogy, motivated by love.
You're welcome.
“Your question seems to assume that one could have, or needs to have, “proof” for pious devotions. This is by noi means the case.”
No friend.
My question assumes you have any evidence at all to substantiate your truth claim about dear Joseph.
I will take your answer to mean you just like the idea.