I think that within the conic sections unit of the precalculus course, an additional topic should be incorporated: rotated conics which occur when the cartesian coordinate system is tilted by an angle to graph a conic. It's a big part of the Honors Precalculus conic sections curriculum at my high school and I feel like it could be a much-needed addition to your already very helpful precalculus course. One more reason I think that the addition of this subtopic to the conic sections unit is essential is that it deals with the "Bxy" term of any given conic.
Also, thank you for providing a vast sea of content spanning countless topics across all fields of academics and beyond. :)