“...fresh eggs keep 6-9 months unrefrigerated if they aren’t washed.”
I take it you mean straight from the chicken eggs. Why do people wash them and why does that affect (effect? not sure this time) their longevity?
My hippie friend actually raised chickens at one point, so I guess I had some of those eggs. She tells me she’s a real prepper now, even though she’s a big lib. (I mean volvo with gaia bumper stickers - literally!) She says she knows most preppers are right wingers, but that doesn’t bother her. I don’t know if she’s still got chickens.
They have a coating on them from the chicken called the bloom that seals the pores in the shell.
They should be treated with mineral oil or use the water glass method though I know some old timers that don't. Just do a search on preserving fresh eggs. Use the water bowl test.