Yes, a new ADU can be built as part of the rebuild and still qualify as a like-for-like +10% project per the Governor's Directive No. N-20-25, regardless of  whether or not an ADU existed on the site prior to the Wildfire.

Eaves: Project into the required side yard not more than 4 inches for each foot of width of such side yard, provided the width of the side yard is not reduced to less than 30 inches. Project into the required front and rear yards not more than 30 inches.