Since the meaning you remember was honestly,"hon" may have been short for
Dated, offensive US
I won't run away, honest Injun Lexico
ORIGIN OF HONEST INJUN 1870–75, Americanism; see Injun
USAGE NOTE FOR HONEST INJUN Honest Injun uses an informal, nonstandard
spelling of Indian. Probably first used by Mark Twain, this expression
is now dated and often perceived as insulting to or by American
Indians. Though it came to mean “honestly or truly,” it may have had
its origin in the contrary perception that Indians on the American
frontier were not considered honest or trustworthy until they had
proven themselves, for example, as scouts. See also Indian.
Although I remember it from my childhood, I would have thought this expression was out-of-date by the early 2000's, but perhaps not, given the date of the Scouting magazine admonition.
"Tom—honest injun, now—is it fun or earnest?" Mark Twain; The Adventures of Tom Sawyer (1876)
"Do yer ask honest Injun, no cheatin' nor nothin?"
Perfectly 'honest Injun.'" Blanche Willard Howard; One Summer
Don't use derogatory words and phrases, such as "Injun," "honest
Injun," "Indian giver," "too many chiefs and not enough Indians," "as
wild as a bunch of Indians," "squaw," "half-breed," or "papoose."
Scouting, Vol. 85, n.6 (1997)