This ancient usage also pops up.
“The phrase has ties to Arthurian lore. A Knight, coming to the service of a damsel would lower his lance and receive a huckleberry garland from the lady ( or kingdom) he would be defending. Therefore, “I am your huckleberry” may well have been spoken to the Earps and the statement’s meaning may be “I am your champion”.”
Boiled down, that was precisely my immediate interpretation. Was there a different one?
Could it also be something like “I’m the huckleberry in your boot” that has just turned into “I’m your huckleberry”?
Don’t know...never thought about any other way!