The resolution of the naked eye is roughly 1 arc minute and the diameter of the sun at 1 AU is roughly 30 times larger. Simple arithmetic suggests that beyond 30 AU looking directly at the Sun might be dazzling but likely not otherwise harmful. The blink reflex will protect you long before retinal burns occur, though there will be localized bleaching which will fix itself within a few minutes.
British Astronomical Association
Supporting amateur astronomers since 1890