I lived in san bruno for a couple years. That area is much more about peninsula style sandwiches - little lucca, mr. pickles, grand leader, roma, etc.
Not a lot of pizza options. They opened a Seniore's on el camino real almost under the 380 overpass. it's cheap, basic, and open really late. There is also some place I never tried on san bruno ave. between the train tracks and 101.
Toto's is on the border of millbrae and san bruno on el camino real. It's probably my favorite thin-crust pizza in the bay area, but i dont think they ever sell by the slice.
La Tapatia in downtown south SF has great take-out taqueria food.
There's also an El Zocalo salvadorian place in south SF.
maybe you already know those.